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We present a detailed study on the temperature-dependent THz spectra of the polycrystalline amino acids, L-serine and L-cysteine, for wavenumbers from 20 to 120 cm−1 and temperatures from 4 to 300 K. Even though the structure of these two amino acids is very similar, with a sulfur atom in the side chain of cysteine instead of an oxygen atom in serine, the excitation spectra are drastically different. Obviously, the vibrational dynamics strongly depend on the ability of cysteine to form sulfur–hydrogen bonds. In addition, cysteine undergoes an order–disorder type phase transition close to 80 K, documented by additional specific heat experiments, with accompanying anomalies in the THz results. On increasing temperatures, well-defined vibrational excitations exhibit significant shifts in the eigenfrequencies with concomitant line-broadening yielding partly overlapping modes. Interestingly, several modes completely lose all their dipolar strength and are unobservable under ambient conditions. Comparing the recent results to the published work utilizing THz, Raman, and neutron-scattering techniques, as well as with ab initio simulations, we aim at a consistent analysis of the results ascribing certain eigenfrequencies to distinct collective lattice modes. We document that THz spectra can be used to fine-tune the parameters of model calculations and as fingerprint properties of certain amino acids. In addition, we analyzed the low-temperature heat capacity of both the compounds and detected strong excess contributions compared to the canonical Debye behavior of crystalline solids, indicating soft excitations and a strongly enhanced phonon-density of states at low frequencies. [ABSTRACT FROM AUTHOR]

Finding low-energy structures of ligand-protected clusters is challenging due to the enormous conformational space and the high computational cost of accurate quantum chemical methods for determining the structures and energies of conformers. Here, we adopted and utilized a kernel rigid regression based machine learning method to accelerate the search for low-energy structures of ligand-protected clusters. We chose the Au25(Cys)18 (Cys: cysteine) cluster as a model system to test and demonstrate our method. We found that the low-energy structures of the cluster are characterized by a specific hydrogen bond type in the cysteine. The different configurations of the ligand layer influence the structural and electronic properties of clusters. [ABSTRACT FROM AUTHOR]

Through mechanistic work and rational design, we have developed the fastest organometallic abiotic Cys bioconjugation. As a result, the developed organometallic Au(III) bioconjugation reagents enable selective labeling of Cys moieties down to picomolar concentrations and allow for the rapid construction of complex heterostructures from peptides, proteins, and oligonucleotides. This work showcases how organometallic chemistry can be interfaced with biomolecules and lead to a range of reactivities that are largely unmatched by classical organic chemistry tools.

Macrophages (MΦ) infected with human immunodeficiency virus (HIV)-1 or activated by its envelope protein gp120 exert neurotoxicity. We found previously that signaling via p38 mitogen-activated protein kinase (p38 MAPK) is essential to the neurotoxicity of HIVgp120-stimulated MΦ. However, the associated downstream pathways remained elusive. Here we show that cysteinyl-leukotrienes (CysLT) released by HIV-infected or HIVgp120 stimulated MΦ downstream of p38 MAPK critically contribute to neurotoxicity. SiRNA-mediated or pharmacological inhibition of p38 MAPK deprives MΦ of CysLT synthase (LTC4S) and, pharmacological inhibition of the cysteinyl-leukotriene receptor 1 (CYSLTR1) protects cerebrocortical neurons against toxicity of both gp120-stimulated and HIV-infected MΦ. Components of the CysLT pathway are differentially regulated in brains of HIV-infected individuals and a transgenic mouse model of NeuroHIV (HIVgp120tg). Moreover, genetic ablation of LTC4S or CysLTR1 prevents neuronal damage and impairment of spatial memory in HIVgp120tg mice. Altogether, our findings suggest a novel critical role for cysteinyl-leukotrienes in HIV-associated brain injury.

Pinpointing functional, structural, and redox-sensitive cysteines is a central challenge of chemoproteomics. Here, we present a protocol comprising two dual-enrichment cysteine chemoproteomic techniques that enable capture of cysteines (Cys-LoC) and quantification of cysteine oxidation state (Cys-LOx) in a localization-specific manner. We describe steps for utilizing TurboID-mediated protein biotinylation for enrichment of compartment-specific proteins, followed by click-mediated biotinylation and enrichment of cysteine-containing peptides. Thus, changes to compartment-specific cysteine identification and redox state can be assessed in a variety of contexts. For complete details on the use and execution of this protocol, please refer to Yan et al. (2023).1.

Listeria monocytogenes (Lm) is a Gram-positive facultative intracellular pathogen that leads a biphasic lifecycle, transitioning its metabolism and selectively inducing virulence genes when it encounters mammalian hosts. Virulence gene expression is controlled by the master virulence regulator PrfA, which is allosterically activated by the host- and bacterially derived glutathione (GSH). The amino acid cysteine is the rate-limiting substrate for GSH synthesis in bacteria and is essential for bacterial growth. Unlike many bacteria, Lm is auxotrophic for cysteine and must import exogenous cysteine for growth and virulence. GSH is enriched in the host cytoplasm, and previous work suggests that Lm utilizes exogenous GSH for PrfA activation. Despite these observations, the import mechanism(s) for GSH remains elusive. Analysis of known GSH importers predicted a homologous importer in Lm comprised of the Ctp ABC transporter and the OppDF ATPases of the Opp oligopeptide importer. Here, we demonstrated that the Ctp complex is a high-affinity GSH/GSSG importer that is required for Lm growth at physiologically relevant concentrations. Furthermore, we demonstrated that OppDF is required for GSH/GSSG import in an Opp-independent manner. These data support a model where Ctp and OppDF form a unique complex for GSH/GSSG import that supports growth and pathogenesis. In addition, we show that Lm utilizes the inorganic sulfur sources thiosulfate and H2S for growth in a CysK-dependent manner in the absence of other cysteine sources. These findings suggest a pathoadaptive role for partial cysteine auxotrophy in Lm, where locally high GSH/GSSG or inorganic sulfur concentrations may signal arrival to distinct host niches.

We performed experiments searching for chirality-dependent secondary electron emission for a 141 eV longitudinally spin-polarized electron beam incident on a thick solid cysteine target. We determined the secondary electron yield by measuring the positive current produced when the cysteine target was negatively biased. No spin-dependent effects to a level of 10−3 were found for the secondary electron emission yield. [ABSTRACT FROM AUTHOR]

• It emphasizes the critical importance of novel therapeutic approaches. • It is the first to discusses the functions of L-cysteine in the anxiety. • It provides an overview of the basic features of L-cysteine. • It presents potential mechanism of L-cysteine in the treatment of anxiety. • It reviews the pathogenesis and neuroanatomical basis of anxiety disorders. Anxiety disorders are prevalent chronic psychological disease with complex pathogenic mechanisms. Current anxiolytics have limited efficacy and numerous side effects in many anxiety patients, highlighting the urgent need for new therapies. Recent research has been focusing on nutritional supplements, particularly amino acids, as potential therapies for anxiety disorders. Among these, L-Cysteine plays a crucial role in various biological processes. L-Cysteine exhibits antioxidant properties that can enhance the antioxidant functions of the central nervous system (CNS). Furthermore, metabolites of L-cysteine, such as glutathione and hydrogen sulfide have been shown to alleviate anxiety through distinct molecular mechanisms. Long-term administration of L-Cysteine has anxiolytic, antidepressant, and memory-improving effects. L-Cysteine depletion can lead to increased oxidative stress in the brain. This review delves into the potential mechanisms of L-Cysteine and its main products, glutathione (GSH) and hydrogen sulfide (H2S) in the management of anxiety and related diseases. [ABSTRACT FROM AUTHOR]

Reformulation with addition of antioxidants is one potential mitigation strategy to prevent or reduce nitrosamine drug substance-related impurities (NDSRIs) in drug products. To explore whether there could be other approaches to demonstrate bioequivalence for a reformulated oral product, which typically needs in vivo bioequivalence studies to support the changes after approval, the effects of antioxidant on the in vitro permeability of BCS III model drug substances were investigated to see whether there could be any potential impact on drug absorption. Six antioxidants were screened and four (ascorbic acid, cysteine, α-tocopherol and propyl gallate) were selected based on their nitrosamine inhibition efficiencies. The study demonstrated that these four antioxidants, at the tested amounts, did not have observable impact on the in vitro permeability of the BCS III model drug substances across Caco-2 cell monolayers in the In Vitro Dissolution Absorption System (IDAS). An in vitro permeability study could be considered as part of one potential bioequivalence bridging approach for reformulated low-risk immediate release solid oral products and oral suspension products. Other factors such as the influence of antioxidants on intestinal transporter activities should be considered where appropriate. [ABSTRACT FROM AUTHOR]

BACKGROUND: High moisture meat analog (HMMA) products processed using extrusion have become increasingly popular in the last few years. Because the formation of disulfide bonds is believed to play a critical role in the texturization mechanism, this study aimed to understand how chemical compounds capable of reducing disulfide bonds, specifically cysteine, sodium metabisulfite, and glutathione, affect the texture and the chemical interactions between the proteins. METHOD: Wheat protein blended with cysteine, sodium metabisulfite, or glutathione at levels of 0, 0.5, 1.0, 2.5, 5.0, and 7.5 g kg−1 was extruded at three different temperatures (115, 140, and 165 °C) using a co‐rotating twin‐screw extruder. The feed rate (85 g min−1), the moisture content (600 g kg−1), and the screw speed (300 rpm) were kept constant. Unextruded and extruded material was subjected to sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, polymeric protein fractionation, and sulfhydryl group/disulfide bond analysis. Extruded samples were further analyzed for their hardness and their anisotropic index. RESULTS: The inclusion of reductants significantly affected the structure of the obtained extrudates. Although reducing agents had a relatively small impact on the total amount of disulfide bonds, their action significantly enhanced crosslinking between the proteins. At select conditions, samples with high fibrousness were specifically obtained when cysteine or sodium metabisulfite was included at levels of 5.0 g kg−1. DISCUSSION: In the presence of reducing agents, it is believed that disulfide bonds are split earlier during the process without binding to them, giving the protein strands more time to unravel and align, leading to a better flow behavior and more fibrous products. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Hadal zones account for the deepest 45% of the oceanic depth range and play an important role in ocean biogeochemical cycles. As the least-explored aquatic habitat on earth, hadal ecosystems contain a vast diversity of so far uncultured microorganisms that cannot be grown on conventional laboratory culture media. Therefore, it has been difficult to gain a true understanding of the detailed metabolic characteristics and ecological functions of those difficult-to-culture microorganisms in hadal environments. In this study, a novel anaerobic bacterial strain, MT110T, was isolated from a hadal sediment--water interface sample of the Mariana Trench at 10,890 m. The level of 16S rRNA gene sequence similarity and percentage of conserved proteins between strain MT110T and the closest relatives, Anaerovorax odorimutans DSM 5092T (94.9 and 46.6%) and Aminipila butyrica DSM 103574T (94.4 and 46.7%), indicated that strain MT110T exhibits sufficient molecular differences for genus-level delineation. Phylogenetic analyses based on both 16S rRNA gene and genome sequences showed that strain MT110T formed an independent monophyletic branch within the family Anaerovoracaceae. The combined evidence showed that strain MT110T represents a novel species of a novel genus, proposed as Anoxybacterium hadale gen. nov. sp. nov. (type strain MT110T = KCTC 15922T = MCCC 1K04061T), which represents a previously uncultured lineage of the class Clostridia. Physiologically, no tested organic matter could be used as sole carbon source by strain MT110T. Genomic analysis showed that MT110T had the potential capacity of utilizing various carbon sources, but the pathways of sulfur reduction were largely incomplete. Our experiments further revealed that cysteine is one of the essential nutrients for the survival of strain MT110T, and cannot be replaced by sulfite, leucine, or taurine. This result suggests that organic sulfur compounds might play an important role in metabolism and growth of the family Anaerovoracaceae and could be one of the key factors affecting the cultivation of the uncultured microbes. Our study brings a new perspective to the role of dissolved organic sulfur in hadal ecosystems and also provides valuable information for optimizing the conditions of isolating related microbial taxa from the hadal environment. [ABSTRACT FROM AUTHOR]

An imbalance in cysteine (Cys) levels in the cells and plasma has been identified as the risk indicator for various human diseases. The structural similarity of cysteine with its congener homocysteine and glutathione offers challenges in its measurement. Herein, we report a hydrogen‐bonded organic‐inorganic framework of Cu(II) (HOIF) for the selective detection of cysteine over other biothiols. The non‐fluorescent HOIF showed 12‐fold green emission in the presence of cysteine. The monomeric unit of HOIF is stabilized via intermolecular hydrogen bonds, resulting in a non‐porous network structure. Non‐interference from homocysteine, glutathione, and other competitive bio‐analytes revealed explicit affinity of HOIF for cysteine. Fluorimetric titration showed a wide working concentration window (650 nM–800 μM) for measuring cysteine in an aqueous medium. The mechanistic investigation involving HRMS, EPR, and UV‐vis spectroscopic studies revealed the decomplexation of HOIF with Cys, resulting in a fluorescence turn‐on response from the luminescent ligand. Validation using a commercial dye, “Cysteine Green”, confirmed the prospect of HOIF for early diagnostic purposes. Utilizing the fluorescence turn‐on property of HOIF in the presence of cysteine, we measured cysteine quantitatively in the blood plasma samples. Bio‐imaging of endogenous cysteine in cancer cells indicated the ability of HOIF to monitor the intracellular cysteine. [ABSTRACT FROM AUTHOR]

Chemoselective modification of specific residues within a given protein poses a significant challenge, as the microenvironment of amino acid residues in proteins is variable. Developing a universal molecular platform with tunable chemical warheads can provide powerful tools for precisely labeling specific amino acids in proteins. Cysteine and lysine are hot targets for chemoselective modification, but current cysteine/lysine‐selective warheads face challenges due to cross‐reactivity and unstable reaction products. In this study, a versatile fluorescent platform is developed for highly selective modification of cysteine/lysine under biocompatible conditions. Chloro‐ or phenoxy‐substituted NBSe derivatives effectively labeled cysteine residues in the cellular proteome with high specificity. This finding also led to the development of phenoxy‐NBSe phototheragnostic for the diagnosis and activatable photodynamic therapy of GSH‐overexpressed cancer cells. Conversely, alkoxy‐NBSe derivatives are engineered to selectively react with lysine residues in the cellular environment, exhibiting excellent anti‐interfering ability against thiols. Leveraging a proximity‐driven approach, alkoxy‐NBSe probes are successfully designed to demonstrate their utility in bioimaging of lysine deacetylase activity. This study also achieves integrating a small photosensitizer into lysine residues of proteins in a regioselective manner, achieving photoablation of cancer cells activated by overexpressed proteins. [ABSTRACT FROM AUTHOR]

Pseudocontact shifts (PCS) generated by paramagnetic lanthanide ions deliver powerful restraints for protein structure analysis by NMR spectroscopy. We present a new lanthanide tag that generates different PCSs than that of a related tag, which differs in structure by a single oxygen atom. It is highly reactive towards cysteine and performs well in turn-on luminescence and in EPR spectroscopy. [ABSTRACT FROM AUTHOR]

Background and Purpose: The analgesic action of paracetamol involves KV7 channels, and its metabolite N‐acetyl‐p‐benzo quinone imine (NAPQI), a cysteine modifying reagent, was shown to increase currents through such channels in nociceptors. Modification of cysteine residues by N‐ethylmaleimide, H2O2, or nitric oxide has been found to modulate currents through KV7 channels. The study aims to identify whether, and if so which, cysteine residues in neuronal KV7 channels might be responsible for the effects of NAPQI. Experimental Approach: To address this question, we used a combination of perforated patch‐clamp recordings, site‐directed mutagenesis, and mass spectrometry applied to recombinant KV7.1 to KV7.5 channels. Key Results: Currents through the cardiac subtype KV7.1 were reduced by NAPQI. Currents through all other subtypes were increased, either by an isolated shift of the channel voltage dependence to more negative values (KV7.3) or by such a shift combined with increased maximal current levels (KV7.2, KV7.4, KV7.5). A stretch of three cysteine residues in the S2‐S3 linker region of KV7.2 was necessary and sufficient to mediate these effects. Conclusion and Implication: The paracetamol metabolite N‐acetyl‐p‐benzo quinone imine (NAPQI) modifies cysteine residues of KV7 subunits and reinforces channel gating in homomeric and heteromeric KV7.2 to KV7.5, but not in KV7.1 channels. In KV7.2, a triple cysteine motif located within the S2‐S3 linker region mediates this reinforcement that can be expected to reduce the excitability of nociceptors and to mediate antinociceptive actions of paracetamol. [ABSTRACT FROM AUTHOR]

Late-stage specific and selective diversifications of peptides and proteins performed at target residues under ambient conditions are recognized to be the most facile route to various and abundant conjugates. Herein, we report an orthogonal modification of cysteine residues using alkyl thianthreium salts, which proceeds with excellent chemoselectivity and compatibility under mild conditions, introducing a diverse array of functional structures. Crucially, multifaceted bioconjugation is achieved through clickable handles to incorporate structurally diverse functional molecules. This "two steps, one pot" bioconjugation method is successfully applied to label bovine serum albumin. Therefore, our technique is a versatile and powerful tool for late-stage orthogonal bioconjugation. Late-stage specific and selective modifications of peptides and proteins at target residues under ambient conditions are the most facile routes to various bioconjugates. Here, the authors report an orthogonal modification of cysteine residues using alkyl thianthreium salts, which proceeds with excellent chemoselectivity and compatibility under mild conditions, introducing a diverse array of functional structures. [ABSTRACT FROM AUTHOR]

Background: The prevalence of sarcopenia is increasing in worldwide with accelerated aging process. The high dietary protein intakes are associated with improved muscle mass and strength especially in Asian countries. However, there are few researches on amino acid levels or mechanism exploration. We conducted a case-control study to explore the amino acid metabolic characteristics and potential mechanism of elderly women with sarcopenia using targeted amino acid metabolomics approach combined with an analysis of dietary intake. Methods: For our case-control study, we recruited women (65–75 y) from a Shanghai community with 50 patients with sarcopenia and 50 healthy controls. The consensus updated by the Asian Working Group on Sarcopenia in 2019 was used to screening for sarcopenia and control groups. We collected fasting blood samples and evaluated dietary intake. We used the amino acid-targeted metabolomics by ultra performance liquid chromatography tandem mass spectrometry to identify metabolic differentials between the case and control groups and significantly enriched metabolic pathways. Results: The case (sarcopenia) group had a lower intake of energy, protein, and high-quality protein (P < 0.05) compared to the control (healthy) group. We identified four differential amino acids: arginine (P < 0.001) and cystine (P = 0.003) were lower, and taurine (P = 0.001) were higher in the case group. Conclusion: Low levels of arginine in elderly women are associated with a higher risk of sarcopenia. [ABSTRACT FROM AUTHOR]

Background: Secreted protein acidic and rich in cysteine (SPARC) has been shown to modulate aggressive behavior in several benign and malignant tumors. Little is known about SPARC expression in odontogenic keratocyst (OKC), an odontogenic cyst with an aggressive nature. To the best of our knowledge, only one study has been investigated the expression of this protein in OKCs. This study aimed to characterize SPARC expression in OKCs. Additionally, to determine whether SPARC is associated with aggressive behavior in OKCs, SPARC expression in OKCs was compared with radicular cysts (RCs), dentigerous cysts (DCs) and calcifying odontogenic cysts (COCs). These odontogenic cysts showed no or less aggressive behavior. Methods: SPARC expression was evaluated in 38 OKCs, 39 RCs, 35 DCs and 14 COCs using immunohistochemistry. The percentages of positive cells and the intensities of immunostaining in the epithelial lining and the cystic wall were evaluated and scored. Results: Generally, OKCs showed similar staining patterns to RCs, DCs and COCs. In the epithelial lining, SPARC was not detected, except for ghost cells in all COCs. In the cystic wall, the majority of positive cells were fibroblasts. Compared between 4 groups of odontogenic cysts, SPARC expression in OKCs was significantly higher than those of RCs (P < 0.001), DCs (P < 0.001) and COCs (P = 0.001). Conclusions: A significant increase of SPARC expression in OKCs compared with RCs, DCs and COCs suggests that SPARC may play a role in the aggressive behavior of OKCs. [ABSTRACT FROM AUTHOR]

Cysteine thiols are susceptible to various oxidative posttranslational modifications (PTMs) due to their high chemical reactivity. Thiol‐based PTMs play a crucial role in regulating protein functions and are key contributors to cellular redox signaling. Although reversible thiol‐based PTMs, such as disulfide bond formation, S‐nitrosylation, and S‐glutathionylation, have been extensively studied for their roles in redox regulation, thiol sulfinic acid (–SO2H) modification is often perceived as irreversible and of marginal significance in redox signaling. Here, we revisit this narrow perspective and shed light on the redox regulatory roles of –SO2H in plant stress signaling. We provide an overview of protein sulfinylation in plants, delving into the roles of hydrogen peroxide‐mediated and plant cysteine oxidase‐catalyzed formation of –SO2H, highlighting the involvement of –SO2H in specific regulatory signaling pathways. Additionally, we compile the existing knowledge of the –SO2H reducing enzyme, sulfiredoxin, offering insights into its molecular mechanisms and biological relevance. We further summarize current proteomic techniques for detecting –SO2H and furnish a list of experimentally validated cysteine –SO2H sites across various species, discussing their functional consequences. This review aims to spark new insights and discussions that lead to further investigations into the functional significance of protein –SO2H‐based redox signaling in plants. Summary statement: This review expands upon the conventional understanding of cysteine thiol sulfinic acid modification and provides an updated overview of its redox‐dependent regulatory functions in the context of plant stress signaling pathways. [ABSTRACT FROM AUTHOR]

The toxicity of silver nanoparticles (AgNPs) depends on their physicochemical properties. The ongoing research aims to develop effective methods for modifying AgNPs using molecules that enable control over the processes induced by nanoparticles in both normal and cancerous cells. Application of amino acid-stabilized nanoparticles appears promising, exhibiting tunable electrokinetic properties. Therefore, this study focused on determining the influence of the surface charge of cysteine (CYS)-stabilized AgNPs on their toxicity towards human normal B (COLO-720L) and T (HUT-78) lymphocyte cell lines. CYS-AgNPs were synthesized via the chemical reduction. Transmission electron microcopy (TEM) imaging revealed that they exhibited a quasi-spherical shape with an average size of 18 ± 3 nm. CYS-AgNPs remained stable under mild acidic (pH 4.0) and alkaline (7.4 and 9.0) conditions, with an isoelectric point observed at pH 5.1. Following a 24 h treatment of lymphocytes with CYS-AgNPs, concentration-dependent alterations in cell morphology were observed. Positively charged CYS-AgNPs notably decreased lymphocyte viability. Furthermore, they exhibited grater genotoxicity and more pronounced disruption of biological membranes compared to negatively charged CYZ-AgNPs. Despite both types of AgNPs interacting similarly with fetal bovine serum (FBS) and showing comparable profiles of silver ion release, the biological assays consistently revealed that the positively charged CYS-AgNPs exerted stronger effects at all investigated cellular levels. Although both types of CYS-AgNPs have the same chemical structure in their stabilizing layers, the pH-induced alterations in their surface charge significantly affect their biological activity. [ABSTRACT FROM AUTHOR]

A novel accelerator, cerium cysteine (Ce-Cys) was synthesised by double replacement reaction. The complex was characterised by FT-IR analysis, thermal analysis, EDTA titration and elemental analysis, respectively, to determine that the molecular formula of the complex was Ce (Cys)3Cl3·3H2O. Cure characteristics, crosslink density, mechanical properties and thermo-oxidative ageing of NR compounds were investigated. The research revealed that the vulcanisates containing Ce-Cys manifested high scorch time, outstanding mechanical properties, and better thermo-oxidative ageing properties. Furthermore, based on kinetic calculations, it was concluded that as the amount of Ce-Cys increased, the reactivity of the crosslink precursor increased while the activation energy decreased. [ABSTRACT FROM AUTHOR]

Antioxidants agents play an essential role in the food industry for improving the oxidative stability of food products. In the last years, the search for new natural antioxidants has increased due to the potential high toxicity of chemical additives. Therefore, the synthesis and evaluation of the antioxidant activity in peptides is a field of current research. In this study, we performed a Quantitative Structure Activity Relationship analysis (QSAR) of cysteine-containing 19 dipeptides and 19 tripeptides. The main objective is to bring information on the relationship between the structure of peptides and their antioxidant activity. For this purpose, 1D and 2D molecular descriptors were calculated using the PaDEL software, which provides information about the structure, shape, size, charge, polarity, solubility and other aspects of the compounds. Different QSAR model for di- and tripeptides were developed. The statistic parameters for di-peptides model (R2train = 0.947 and R2test = 0.804) and for tripeptide models (R2train = 0.923 and R2test = 0.847) indicate that the generated models have high predictive capacity. Then, the influence of the cysteine position was analyzed predicting the antioxidant activity for new di- and tripeptides, and comparing them with glutathione. In dipeptides, excepting SC, TC and VC, the activity increases when cysteine is at the N-terminal position. For tripeptides, we observed a notable increase in activity when cysteine is placed in the N-terminal position. [ABSTRACT FROM AUTHOR]

Pictet-Spengler reaction is one of the main ways to synthesize spiroindolones, which widely exists in natural products and pharmaceutical agents. We accidentally discovered bovine serum albumin (BSA) had catalytic activity for Pictet-Spengler reaction previously. After a series of exploratory experiments around the catalytic process, it was found that some amino acids played a key role. It is worth noting that, Pictet-Spengler reaction catalyzed by amino acids has been rarely described. Herein, we report the cysteine-catalyzed Pictet-Spengler reaction between tryptamine and isatin under metal-free and convenient conditions. The catalytic performance of amino acid was optimized through screening reaction conditions such as time, temperature, solvent, molar ratio and catalyst amount and a series of spiroindolones can be obtained in moderate to excellent yields. The present investigation featured relatively mild reaction conditions with good functional group tolerance and provided an alternative method for preparation of spiroindolones. [ABSTRACT FROM AUTHOR]

Modern society's keen regard for aesthetics made hair products an integral part of a multi‐billion‐dollar cosmetic industry. Hair care products (e.g., shampoos and conditioners) and chemical treatments (e.g., bleaching and permanent waving) result in various effects on the morphological attributes of hair. Generally, water adsorbed on the hair surface is known to significantly dictate the hair's mechanical characteristics (smoothness and friction), and hair's macroscopic wettability has been commonly used to indicate its surface properties. However, an approach to selectively characterize the hydration water in the hair surface is required to accurately understand the intermolecular events between the hair and its vicinal water. In this paper, we successfully obtained the infrared (IR) absorption spectra of the hydration water of human hair. We employed the multivariate curve resolution‐alternating least square (MCR‐ALS) method to separate the hydration and bulk water spectra from the whole spectra. Comparing the IR spectra of the hydration water of chemically untreated and bleached hair samples, we conclude that water molecules form strong hydrogen bonds with the bleached hair surface due to the destruction of the hair's hydrophobic outer layer and the consequent formation of hydrophilic residues. [ABSTRACT FROM AUTHOR]

Much progress has been made in the determination of As (III), while numerous electrochemical sensors based on metal nanomaterials with significant sensitivity and precision have been developed. However, further research is still required to achieve rapid detection and avoid interference from other metal ions (especially copper ions). In this study, bimetallic AuPt nanoparticles are electrochemically modified with screen printing electrodes. What's more, L-cysteine also self-assembles with AuNPs through Au-S bond to enhance the electrochemical performance. To overcome the interference of Cu (II) in the sensing process, the reduced iron powder was chosen to remove Cu (II) and other oxidizing organics in aqueous solutions. The lowest detectable amount is 0.139 ppb, a linear range of 1~50 ppb with superlative stability by differential pulse anodic stripping voltammetry. Fortunately, the reduced iron powder could eliminate the Cu (II) with no effect on the As (III) signal. [ABSTRACT FROM AUTHOR]

Purpose: The Cr(VI) removal capacity of green synthesized nano-zero-valent iron (GnZVI) using tea polyphenols (TPs) remains limited. To improve their application in contaminated soil and groundwater, the GnZVI was modified. This is necessary for in-situ remediation of heavy metal-contaminated soil and groundwater. Materials and methods: The GnZVI-based carbon-composite (L&GnZVI@BC) was successfully constructed via the synergistic effect of L-cysteine modification and biochar support. The Cr(VI) removal capacity and transportability of L&GnZVI@BC were investigated in soil–water system by batch and column experiments. Results and discussion: Comparison with two materials of GnZVI separately modified by L-cysteine (L-GnZVI) or supported by biochar (GnZVI@BC)), GnZVI composite with a combination modification of L-cysteine and biochar (L&GnZVI@BC, L-cysteine/biochar/Fe = 0.1/0.1/1) showed a much higher Cr(VI) removal capacity in soil and groundwater. The synergistic effect of the reduction of L-cysteine functional groups and the dispersibility of biochar support can enhance the transportability of L&GnZVI@BC in water-saturated sand media for more Cr(VI) adsorption at neutral pH; while that improved the soluble Fe(II) released from composite for the higher reduction of Cr(VI) into Cr(III) at acidic pH. Particularly, L&GnZVI@BC favored more Cr(III) generation during transport in porous media at lower pH when applied in the treatment of Cr(VI) contamination. Conclusion: This research highlights that the modification of both L-cysteine and biochar was beneficial to sufficient transport and efficient remediation in Cr(VI)-contaminated soil and groundwater environments at different pH ranges. This study's results provide a theoretical support for the practical application of nZVI composites in in-situ remediation of Cr(VI)-contaminated soil and groundwater via an environmental-friendly approach. [ABSTRACT FROM AUTHOR]

Semisynthesis using recombinant polypeptides is a powerful approach for the synthesis of proteins having a variety of modifications. Peptide thioesters, of which the peptide C-terminus is activated by a thioester, are utilized for coupling peptide building blocks. Biological methods employing intein have been a center for the C-terminal thioesterification of recombinant polypeptides. Chemical activation has emerged as an alternative methodology for synthesizing peptide thioesters from recombinant polypeptides. Chemical reactions are compatible with various solutions containing organic solvents, chaotropic reagents, or detergents that are generally incompatible with biomolecules such as intein. Despite the potential utility of chemical activation, available methods remain limited. This article introduces the methods for the chemical activation of a peptide C-terminus applied to the chemical synthesis of proteins. By showcasing these methodologies, we aim to accelerate the advancement of new chemical reactions and methodologies and broaden the frontiers for the chemical synthesis of proteins. [ABSTRACT FROM AUTHOR]

Porphyromonas gingivalis is a keystone pathogen in periodontitis, and Streptococcus sanguinis is an abundant oral commensal bacterium associated with periodontal health. However, the interaction between P. gingivalis and S. sanguinis remains obscure. Here, we established a strategy for high‐throughput measurement of the cell number of P. gingivalis in the coculture with S. sanguinis by detecting the concentration of hydrogen sulfate. The interaction between P. gingivalis and over 2000 S. sanguinis single‐gene mutants was characterized using this strategy, and several interaction‐associated genes in S. sanguinis were determined by detecting more P. gingivalis cells in the coculture with matched S. sanguinis mutants. Three S. sanguinis interaction‐associated genes were predicted to be responsible for cysteine metabolism, and the supplementation of exogenous L‐cysteine promoted the cell number of P. gingivalis in the coculture with S. sanguinis. Thus, exogenous L‐cysteine and the compromised cysteine metabolism in S. sanguinis enhanced the growth of P. gingivalis in the existence of S. sanguinis. Additionally, the interaction between P. gingivalis and other Streptococcus spp. was examined, and S. pneumoniae was the only streptococci that had no inhibition on the cell number of P. gingivalis. In total, this study established a new strategy for high‐throughput screening of the interaction between Streptococcus and P. gingivalis and discovered a set of genes in S. sanguinis that impacted the interaction. The influence of exogenous L‐cysteine on the interaction between P. gingivalis and S. sanguinis in the oral cavity needs further investigation. [ABSTRACT FROM AUTHOR]

Alternative day fasting (ADF) has been shown to enhance the lifespan of animals. However, human trials evaluating the efficacy of ADF have only recently emerged, presenting challenges due to the extreme nature of this dietary regimen. To better understand the effects of ADF, we investigated its impact using Caenorhabditis elegans as a model organism. Our findings reveal that ADF extends the lifespan of worms nourished on animal‐based protein source, while those fed with plant‐based protein as the primary protein source do not experience such benefits. Remarkably, initiating ADF during midlife is sufficient to prolong lifespan, whereas implementation during youth results in developmental damage, and in older age, fails to provide additional extension effects. Furthermore, we discovered that midlife ADF up‐regulates the expression of two cysteine protease cathepsin B genes, cpr‐2 and cpr‐5, which preserve lysosomal integrity and enhance its function in digesting aggregated proteins, as well as enhancing lipid metabolism and ameliorating neurodegenerative disease markers and phenomena during aging. This suggests that midlife ADF has long lasting anti‐aging effects and may delay the onset of related diseases, specifically in animals consuming animal‐based protein source. These findings offer valuable insights into the effects of ADF and provide guidance for future research and potential applications in individuals. [ABSTRACT FROM AUTHOR]

Background: Data show that due to endothelial damage and thrombogenic effects, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection may accelerate the development of atherosclerosis and increase the risk of cardiovascular diseases (CVDs). The impaired metabolism of aminothiols increases oxidative stress, as these molecules are involved in antioxidant defense as well as in thiol redox control. In this study, total levels of selected aminothiols (i.e., cysteine (Cys), homocysteine (HCy), and glutathione) in convalescents after coronavirus disease of 2019 (COVID-19) were evaluated. The analyses were made according to the sex of the patients, time from COVID-19 onset, and COVID-19 severity. Methods: The study group consisted of 212 patients after COVID-19. Levels of total aminothiols were assessed in the blood plasma using high-performance liquid chromatography (HPLC). Results: The mean Cys concentrations were higher in men than in women (229.92 µmol/L ± 51.54 vs. 210.35 µmol/L ± 41.90, respectively; p = 0.003). Differences in Cys levels were also noticed in the total study group between patients distinguished due to time from disease onset (226.82 µmol/L ± 40.57 in <12 weeks, 232.23 µmol/L ± 47.99 in patients 12–24 weeks, and 208.08 µmol/L ± 48.43 in patients >24 weeks; p = 0.005). In addition, over 11% of total patients 12–24 weeks from disease onset had Cys levels above 300 µmol/L compared to almost 4% of patients <12 weeks and 2% of patients >24 weeks (p = 0.046). In sex-adjusted subgroups, significant differences due to time from COVID-19 were found in Cys levels in women (p = 0.004) and in glutathione levels in men (p = 0.024). None of the aminothiol levels differed between the subgroups based on the severity of COVID-19. Conclusions: Men had overall higher Cys levels than women. Cys levels were lower >24 weeks after COVID-19 onset than in the earlier period after disease onset. A partial elevation in Cys levels 12–24 weeks after the disease onset may contribute to the increase in CVD risk in the post-COVID-19 period. [ABSTRACT FROM AUTHOR]

The ninhydrin reaction is commonly used for the detection of amino acids. However, in the literature, different conditions with respect to the buffer system, its pH and concentration, type of organic solvent, incubation time, and temperature, as well as the concentrations of the reagents, are described. To identify the most suitable conditions, colour development with reagents of varying compositions and different reaction temperatures and times were investigated using asparagine as a model amino acid. Asparagine was selected since it is one of the most abundant free amino acids in many types of samples. The optimal reaction mixture consisted of 0.8 mol L−1 potassium acetate, 1.6 mol L−1 acetic acid, 20 mg mL−1 ninhydrin and 0.8 mg mL−1 hydrindantin in DMSO/acetate buffer 40/60 (v/v) (final concentrations). The best reaction condition was heating the samples in 1.5 mL reaction tubes to 90 °C for 45 min. Afterwards, the samples were diluted with 2-propanol/water 50/50 (v/v) and the absorbance was measured at 570 nm. The proteinogenic amino acids showed a similar response except for cysteine and proline. The method was highly sensitive and showed excellent linearity as well as intra-day and inter-day reproducibility. [ABSTRACT FROM AUTHOR]

Non-enzyme-catalyzed thiol addition onto the α,β-unsaturated carbonyl system is associated with several biological effects. Kinetics and diastereoselectivity of non-enzyme catalyzed nucleophilic addition of reduced glutathione (GSH) and N-acetylcysteine (NAC) to the six-membered cyclic chalcone analogs 2a and 2b were investigated at different pH values (pH 3.2, 7.4 and 8.0). The selected compounds displayed in vitro cancer cell cytotoxicity (IC50) of different orders of magnitude. The chalcones intrinsically reacted with both thiols under all incubation conditions. The initial rates and compositions of the final mixtures depended both on the substitution and the pH. The stereochemical outcome of the reactions was evaluated using high-pressure liquid chromatography with UV detection (HPLC-UV). The structures of the formed thiol-conjugates and the retro-Michael products (Z)-2a and (Z)-2b were confirmed by high-pressure liquid chromatography-mass spectrometry (HPLC-MS). Frontier molecular orbitals and the Fukui function calculations were carried out to investigate their effects on the six-membered cyclic analogs. Data were compared with those obtained with the open-chain (1) and the seven-membered (3) analogs. The observed reactivities do not directly relate to the difference in in vitro cancer cell cytotoxicity of the compounds. [ABSTRACT FROM AUTHOR]

A facilely prepared composite based on Polyvinyl alcohol anchored‐ L‐cysteine (PVA‐L‐CYS) demonstrated efficient functionality in the elimination of heavy metals (Hg, Cr, Pb, and Cd) from working wastewater. The synthesis of the composite was validated through a comprehensive characterization utilizing various analytical techniques to ensure the composite's structural, chemical, and physical properties. At ambient temperature, pH of 4–5.5, interaction time of 15–20 minutes, and concentration of 200 mg/L metal ions, the composite exhibited a maximum retention capacity of 48.5, 25, 45.25, and 44.25 mg/g for Hg, Cr, Pb, and Cd, respectively. Langmuir modeling was establish to be more fitting to the practical results than Freundlich, providing theoretical values of 49.02, 25.97, 46.08, and 44.84 mg/g for Hg, Cr, Pb, and Cd, respectively. The kinetics of PVA‐L‐CYS composite was accurately predicted by model of the pseudo‐first‐order kinetic. Thermodynamic prospects indicated a spontaneous, exothermic, and favorable uptake process at low temperatures. Efficient elution of the heavy metal ions from the overloaded composite was performed using 1 M HNO3. In accordance with WHO and FAO guidelines, the successful elimination of working metal ions from wastewater utilizing the PVA‐L‐CYS composite was demonstrated in a single cycle before discharge into the marine environment. [ABSTRACT FROM AUTHOR]

An advanced insulin synthesis is presented that utilizes one‐pot/stepwise disulfide bond formation enabled by acid‐activated S‐protected cysteine sulfoxides in the presence of chloride anion. S‐chlorocysteine generated from cysteine sulfoxides reacts with an S‐protected cysteine to afford S‐sulfenylsulfonium cation, which then furnishes the disulfide or reversely returns to the starting materials depending on the S‐protection employed and the reaction conditions. Use of S‐acetamidomethyl cysteine (Cys(Acm)) and its sulfoxide (Cys(Acm)(O)) selectively give the disulfide under weak acid conditions in the presence of MgCl2 even if S‐p‐methoxybenzyl cysteine (Cys(MBzl)) and its sulfoxide (Cys(MBzl)(O)) are also present. In contrast, the S‐MBzl pair yields the disulfide under more acidic conditions in the presence of a chloride anion source. These reaction conditions allowed a one‐pot insulin synthesis. Additionally, lipidated insulin was prepared by a one‐pot disulfide‐bonding/lipidation sequence. [ABSTRACT FROM AUTHOR]

The knowledge regarding the origins of life from inanimate materials is still elusive. It was proposed that biological building blocks evolved from the inorganic substances present in the early earth conditions. However, the process by which chemistry can be converted into biology has not yet been achieved in the laboratory. The artificial system in the out‐of‐equilibrium state must maintain a few critical features of life, like compartmentalization, metabolism, and replication, to be considered alive. In this direction, working with cysteine (Cys)‐based molecules is strategic to understand the life evolution process. The presence of the sulphydryl (−SH) group in the Cys‐residue can build a dynamic equilibrium state through disulfide redox chemistry under the proper guidance of oxidizing and reducing agents. In this review article, our primary focus is to discuss the Cys‐containing short‐peptide‐based self‐assembly and disassembly processes. The formation of disulfide bonds sometimes helps in the self‐assembly process and gelation, but the reverse is also true in some cases. In the later part of this article, we cover the fact that these sulphydryl‐based systems have shown their adaptability to mimic different life‐essential criteria to participate in Darwinian evolution. [ABSTRACT FROM AUTHOR]

Background: Lentil is an important legume crop and plays an important role in human nutrition and soil fertility improvement. It contains 57-60% carbohydrate, 24-26% protein, 3.2% fiberand only 1.3% fat with the full complement of amino acids. It is a potential crop for about 10 million hectares of rice-fallow areas of eastern India. This study aimed to standardized sulphur and boron requirements of lentil in Eastern India. Methods: The experiment was conducted in a glass house during 2018-19 and 2019-20 in a factorial completely randomized design with three replications and 16 treatment combinations of sulphur and boron. The treatment combinations were product of 4 levels each of sulphur and boron as 0, 15, 30 and 45 kg ha-1 (0, 0.067, 0.134 and 0.201 g pot-1) and 0, 1, 2 and 3 kg ha-1 (0, 0.004, 0.009 and 0.013 g pot-1), respectively. Lentil grain yield was observed at harvest and sulphur-containing amino acids, as well as seed nutrient content, were analyzed followingstandard operating procedures. Result: Lentil grain yield was enhanced by 1.85 times with a combined application of 45 kg S and 2 kg B ha-1 with a recommended dose of NPK. The sulphur-containing amino acids namely methionine, cystine and cysteine content showed significant improvement with increasing levels of sulphur application however were not significantly affected with boron levels. The protein content in lentil seed increased considerably with application of sulphur levels as compared to boron levels and it was highest with 30 kg S ha-1 + 2kg B ha-1 along with recommended dose of NPK fertilizers. [ABSTRACT FROM AUTHOR]

Hemicyanine dyes are an ideal structure for building near-infrared fluorescent probes due to their excellent emission wavelength properties and biocompatibility in biological imaging field. Developing a near-infrared fluorescent probe capable of detecting cysteine (Cys) was the aim of this study. A novel developed fluorescent probe P showed high selectivity and sensitivity to Cys in the presence of various analytes. The detection limit of P was found to be 0.329 μM. The MTT assay showed that the probe was essentially non-cytotoxic. Furthermore, the probe was successfully used as cysteine imaging in living cells and mice. [ABSTRACT FROM AUTHOR]

Oxidative stress is involved in the development of several pathologies. The different reactive oxygen species (ROS) produced during oxidative stress are at the origin of redox post-translational modifications (PTMs) on proteins and impact nucleic acids and lipids. This review provides an overview of recent data on cysteine and methionine oxidation and protein carbonylation following oxidative stress in a pathological context. Oxidation, like nitration, is a selective process and not all proteins are impacted. It depends on multiple factors, including amino acid environment, accessibility, and physical and chemical properties, as well as protein structures. Thiols can undergo reversible oxidations and others that are irreversible. On the contrary, carbonylation represents irreversible PTM. To date, hundreds of proteins were shown to be modified by ROS and reactive nitrogen species (RNS). We reviewed recent advances in the impact of redox-induced PTMs on protein functions and activity, as well as its involvement in disease development or treatment. These data show a complex situation of the involvement of redox PTM on the function of targeted proteins. Many proteins can have their activity decreased by the oxidation of cysteine thiols or methionine S-methyl thioethers, while for other proteins, this oxidation will be activating. This complexity of redox PTM regulation suggests that a global antioxidant therapeutic approach, as often proposed, is unlikely to be effective. However, the specificity of the effect obtained by targeting a cysteine or methionine residue to be able to inactivate or activate a particular protein represents a major interest if it is possible to consider this targeting from a therapeutic point of view with our current pharmacological tools. Antioxid. Redox Signal. 41, 152–180. [ABSTRACT FROM AUTHOR]

Naturally occurring gain-of-function (GOF) mutants have been identified in patients for a variety of cytokine receptors. Although this constitutive activation of cytokine receptors is strongly associated with malignant disorders, ligand-independent receptor activation is also a useful tool in synthetic biology e.g. to improve adoptive cellular therapies with genetically modified T-cells. Balanced Interleukin (IL-)7 signaling via a heterodimer of IL-7 receptor (IL-7Rα) and the common γ-chain (γc) controls T- and B-cell development and expansion, whereas uncontrolled IL-7 signaling can drive acute lymphoid leukemia (ALL) development. The ALL-driver mutation PPCL in the transmembrane domain of IL-7Rα is a mutational insertion of the four amino acids proline-proline-cysteine-leucine and leads to ligand-independent receptor dimerization and constitutive activation. We showed here in the cytokine-dependent pre-B-cell line Ba/F3 that the PPCL-insertion in a synthetic version of the IL-7Rα induced γc-independent STAT5 and ERK phosphorylation and also proliferation of the cells and that booster-stimulation by arteficial ligands additionally generated non-canonical STAT3 phosphorylation via the synthetic IL-7Rα-PPCL-receptors. Transfer of the IL-7Rα transmembrane domain with the PPCL insertion into natural and synthetic cytokine receptor chains of the IL-6, IL-12 and Interferon families also resulted in constitutive receptor signaling. In conclusion, our data suggested that the insertion of the mutated PPCL IL-7Rα transmembrane domain is an universal approach to generate ligand-independent, constitutively active cytokine receptors. [ABSTRACT FROM AUTHOR]

Chinese hamster ovary (CHO) cells require cysteine for growth and productivity in fed-batch cultures. In intensified processes, supplementation of cysteine at high concentrations is a challenge due to its limited solubility and instability in solution. Methionine can be converted to cysteine (CYS) but key enzymes, cystathionine beta-synthase (Cbs) and cystathionine gamma-lyase (Cth), are not active in CHO cells resulting in accumulation of an intermediate, homocysteine (HCY), in cell culture milieu. In this study, Cbs and Cth were overexpressed in CHO cells to confer cysteine prototrophy, i.e., the ability to grow in a cysteine free environment. These pools (CbCt) needed homocysteine and beta-mercaptoethanol (βME) to grow in CYS-free medium. To increase intracellular homocysteine levels, Gnmt was overexpressed in CbCt pools. The resultant cell pools (GnCbCt), post adaptation in CYS-free medium with decreasing residual HCY and βME levels, were able to proliferate in the HCY-free, βME-free and CYS-free environment. Interestingly, CbCt pools were also able to be adapted to grow in HCY-free and CYS-free conditions, albeit at significantly higher doubling times than GnCbCt cells, but couldn't completely adapt to βME-free conditions. Further, single cell clones derived from the GnCbCt cell pool had a wide range in expression levels of Cbs, Cth and Gnmt and, when cultivated in CYS-free fed-batch conditions, performed similarly to the wild type (WT) cell line cultivated in CYS supplemented fed-batch culture. Intracellular metabolomic analysis showed that HCY and glutathione (GSH) levels were lower in the CbCt pool in CYS-free conditions but were restored closer to WT levels in the GnCbCt cells cultivated in CYS-free conditions. Transcriptomic analysis showed that GnCbCt cells upregulated several genes encoding transporters as well as methionine catabolism and transsulfuration pathway enzymes that support these cells to biosynthesize cysteine effectively. Further, 'omics analysis suggested CbCt pool was under ferroptotic stress in CYS-free conditions, which, when inhibited, enhanced the growth and viability of these cells in CYS-free conditions. • Cysteine is difficult to supplement & control in CHO cell processes. • Cth, Cbs, & Gnmt (GnCbCt) or Cth & Cbs (CbCt) overexpression confers CYS prototrophy. • In -CYS, GnCbCt grows better than CbCt & produce titers comparable to WT in +CYS. • GnCbCt express other genes that further enable growth in CYS-free conditions. • CbCt cells appear to be under ferroptotic stress but not GnCbCt cells. [ABSTRACT FROM AUTHOR]

Infectious diseases have been jeopardized problem that threaten public health over a long period of time. The growing prevalence of drug‐resistant pathogens and infectious cases have led to a decrease in the number of effective antibiotics, which highlights the urgent need for the development of new antibacterial agents. Serine acetyltransferase (SAT), also known as CysE in certain bacterial species, and O‐acetylserine sulfhydrylase (OASS), also known as CysK in select bacteria, are indispensable enzymes within the cysteine biosynthesis pathway of various pathogenic microorganisms. These enzymes play a crucial role in the survival of these pathogens, making SAT and OASS promising targets for the development of novel anti‐infective agents. In this comprehensive review, we present an introduction to the structure and function of SAT and OASS, along with an overview of existing inhibitors for SAT and OASS as potential antibacterial agents. Our primary focus is on elucidating the inhibitory activities, structure–activity relationships, and mechanisms of action of these inhibitors. Through this exploration, we aim to provide insights into promising strategies and prospects in the development of antibacterial agents that target these essential enzymes. [ABSTRACT FROM AUTHOR]

Background: Inflammation serves as our body's immune response to combat infections, pathogens, viruses, and external stimuli. Inflammation can be classified into two types: acute inflammation and chronic inflammation. Non-steroidal anti-inflammatory medications (NSAIDs) are used to treat both acute and chronic inflammatory disorders. However, these treatments have various side effects such as reduced healing efficiency, peptic ulcers, gastrointestinal toxicities, etc. Method: This review assesses the potential of anti-inflammatory peptides (AIPs) derived from various natural sources, such as algae, fungi, plants, animals, and marine organisms. Focusing on peptides rich in cysteines and methionine, sulphur-containing amino acids known for their role in suppression of inflammation. Result: Due to their varied biological activity, ability to penetrate cells, and low cytotoxicity, bioactive peptides have garnered interest as possible therapeutic agents. The utilisation of AIPs has shown great potential in the treatment of disorders associated with inflammation. AIPs can be obtained from diverse natural sources such as algae, fungi, plants, and animals. Cysteine and methionine are sulphur-containing amino acids that aid in the elimination of free radicals, hence assisting in the treatment of inflammatory diseases. Conclusion: This review specifically examines several sources of AIPs including peptides that contain numerous cysteines and methionine. In addition, the biological characteristics of these amino acids and advancements in peptide delivery are also discussed. [ABSTRACT FROM AUTHOR]

It has remained unknown how cells reduce cystine taken up from the extracellular space, which is a required step for further utilization of cysteine in key processes such as protein or glutathione synthesis. Here, we show that the thioredoxin-related protein of 14 kDa (TRP14, encoded by TXNDC17) is the rate-limiting enzyme for intracellular cystine reduction. When TRP14 is genetically knocked out, cysteine synthesis through the transsulfuration pathway becomes the major source of cysteine in human cells, and knockout of both pathways becomes lethal in C. elegans subjected to proteotoxic stress. TRP14 can also reduce cysteinyl moieties on proteins, rescuing their activities as here shown with cysteinylated peroxiredoxin 2. Txndc17 knockout mice were, surprisingly, protected in an acute pancreatitis model, concomitant with activation of Nrf2-driven antioxidant pathways and upregulation of transsulfuration. We conclude that TRP14 is the evolutionarily conserved enzyme principally responsible for intracellular cystine reduction in C. elegans, mice, and humans. Synopsis: Metabolic utilization of cysteine requires reduction of cystine taken up from extracellular sources. Here, TXNDC17 -encoded TRP14 is identified as the main enzyme catalyzing this step, regulating protein cysteinylation and cysteine homeostasis in concert with the transsulfuration pathway. Thioredoxin-related protein TRP14 is the rate-limiting enzyme in mammalian cytosolic cystine reduction. Genetic ablation of TRP14 redirects cysteine biosynthesis towards the transsulfuration pathway as alternative, methionine-based source of cysteine. TRP14 also reduces cysteinylated proteins and potentially modulates protein function, such as reactivation of cysteinylated peroxiredoxin 2 through its decysteinylation. Txndc17 -deficient mice are protected from acute pancreatitis pathophysiology through activation of Nrf2-mediated antioxidant pathways and primed upregulation of transsulfuration. Interplay between TRP14 and transsulfuration in cysteine metabolism appears conserved across species, as knockout of both pathways becomes lethal in C. elegans subjected to proteotoxic stress. A thioredoxin-related protein controls cysteine homeostasis in parallel to the transsulfuration pathway, and can also modulate protein function via protein decysteinylation. [ABSTRACT FROM AUTHOR]

Cysteine (Cys) plays an indispensable role as an antioxidant in the maintenance of bioredox homeostasis. We have constructed an efficient fluorescent probe Mito-Cys based on the binding of indole and naphthol. The acrylic ester group serves as a recognition switch for specific detection of Cys, which undergoes Michael addition and intramolecular cyclization reactions, thereby ensuring the chemical kinetics priority of Cys compared to other biothiols. The probe has good water solubility, large Stokes shift (137 nm), with a detection limit of 21.81 nM. In addition, cell imaging experiments have shown that the probe has excellent mitochondrial targeting ability (R = 0.902). The probe can distinguish between Cys, homocysteine (Hcy) and glutathione (GSH), and can detect Cys specifically and quickly (100 s) to ensure accurate quantitative analysis of Cys changes in cells. More importantly, the probe confirms that ferroptosis inducing factors trigger thiol starvation in mitochondria, which helps to gain a deeper understanding of the physiological and pathological functions related to Cys and ferroptosis. [ABSTRACT FROM AUTHOR]

The catalysis of direct thiomethylation of 1H-indole and tryptophan under the action of the formaldehyde—mercaptan reagent system in the presence of acids and bases, phosphorus oxide and the oxidative system I2/NaOH was studied. A mechanism for the catalysis of the multicomponent thiomethylation reaction was proposed based on the results of mass spectrometric study of intermediate compounds. [ABSTRACT FROM AUTHOR]

In artificially controlled pot experiments, perennial ryegrass was mixed with other leguminous plants (white clover and alfalfa) and treated with lead, zinc and cadmium (337 mg·kg, 648 mg·kg, and 9 mg·kg, respectively) to simulate compound pollution conditions. The results showed that the concentrations of heavy metals, transport factors, and bioconcentration factors in mixed planting of ryegrass decreased compared with those in monoculture. Regardless of whether heavy metal pollution was introduced, mixed planting increased the aboveground and underground biomasses of ryegrass. The different mixed planting treatments had no significant impact on the chlorophyll concentration of ryegrass. The mowing time, mixed planting treatment, and heavy metal treatment had impacts on antioxidant and osmotic adjustment substances, and there were some interactions. The mixed planting treatment did not significantly affect glutathione concentration, cysteine concentration, or nonprotein thiol. Mixed planting generally increased the nitrogen and phosphorus concentrations of ryegrass while reducing the stoichiometric ratio of carbon, nitrogen, and phosphorus. These results suggest that the mixed planting of ryegrass with legumes promotes the growth of ryegrass in the presence of high concentrations of heavy metal pollution. However, it does not enhance the ability of ryegrass to remediate heavy metal pollution in the soil. [ABSTRACT FROM AUTHOR]

A digital image colorimetry method utilizing a smartphone as the detection tool was developed for the determination of acetylcysteine and cysteine in effervescent tablets. The method is based on a simple nitroprusside test specific for free −SH groups in aminothiols, which results in orange-red color sample solutions for colorimetric detection. The analytical response of the colorimetric detection decreased as the amino acid concentration increased. The data of the digital images taken were processed to RGB (red–green–blue) color scales using the Color Detector application. Today's technology allows faster and easier analysis with the use of easily accessible and portable smartphones in colorimetric detection systems. The developed method has good linearity in a linear working range of 5.0–25 mg/L (41.27–206.34 µM) and 4.94–47.30 mg/kg (30.27–289.85 µM) for cysteine and acetylcysteine, respectively. The limit of detection and quantification values for cysteine and acetylcysteine were calculated as 1.0 and 3.4 mg/L (8.25–28.06 µM) and 1.8 and 6.1 mg/kg (11.03–37.38 µM), respectively. The applicability and accuracy of the developed method were tested on drug samples. According to the results, this method has the potential to be used in the routine analysis and quality control of pharmaceutical formulations. [ABSTRACT FROM AUTHOR]

Background & Objective: Polycystic ovary syndrome is the prevailing endocrine disorder in females and one of the main causes of anovulatory sterility. It is associated with symptoms, disturbs females of reproductive age and affects their quality of life. Cathepsins are proteases that perform a variety of physiological tasks, including activating the complement system, regulating the immune system, and regulating, tissue homeostasis, and ion channel functioning. There are various subtypes, including aspartic, cysteine, and serine cathepsins. Cat S belongs to the family of cysteine cathepsin proteases. A lysosomal protease can encourage the endo-lysosomal pathway's destruction of undesirable or damaged proteins. The present study was conducted with aim to investigate the relationship between cathepsin S and Insulin Resistance in Iraqi women with PCOS. Materials & Methods: An Observational Case-Control Study was performed. The levels of cathepsin S, Insulin, glucose, and insulin resistance were evaluated for 135 blood samples (90 patients and 45 controls). Cathepsin S and Fasting Insulin were estimated by sandwich ELISA method, while glucose was performed using the COBAS INTEGRA 400 plus analyzer. Insulin resistance was calculated by the HOMA-IR formula. All the test procedures were performed at the College of Medicine’s Research Unit /Al-Nahrain University/ Baghdad-Iraq. The study was conducted from December to the end of March of 2023. Results: The levels of cathepsin S, Insulin, HOMA-IR, and glucose were elevated among PCOS patients with a high significant difference (HS) (P<0.0001) between the patient and the control groups. Conclusion: According to the results of this study, Cat S has the potential to be a novel vital component among PCOS parameters. Insulin Resistance continues to rise among PCOS women leading to a necessity for studying its specific mechanism and its genetic origins. [ABSTRACT FROM AUTHOR]

This article raises the relevancy problems of bimetallic nanostructures using to inhibit corrosion processes specific to various sulfur-containing media, including the extraction and transportation of natural hydrocarbons, in oil and gas condensate equipment. The environmental aspect of the research is the possibility of using bimetallic nanostructures modified with cysteine as environmentally friendly agents that protect steel from corrosion, especially in a thiol medium. There are presented experimental data on the synthesis and study of bimetallic nanostructures based on copper and silver in a thiol medium based on cysteine aminoacid. The research field is conditioned by these days' tendency that advanced developments in many branches of science are directly associated to the application of nanomaterials. The high action efficiency of these materials is achieved due to their highly dispersed state, distinguishing them favorably from conventional macroobjects. The synthesis of Cu/Ag nanostructures was carried out due to the unique properties of bimetals, such as increased activity of atoms in the surface layer, display of quantum effects, etc., that are more pronounced than those in monometallic nanostructures. The main article concept lies within simulation the process of sulfides and other sulfur compounds formation with bimetallic nanoparticles to protect oil and gas equipment from sulfur-containing corrosive agents in aqueous medium. The goal is to synthesize the copper-silver bimetallic microparticles stabilized with apple pectin and verification of the possibility of forming a metal-sulfur bond at the nanoscale level with cysteine aminoacid as a suitable and convenient compound. The objectives include directly the method of synthesis of the bimetallic microstructure Cu-Ag, stabilized with a solution of apple pectin; absorption spectrophotometry of the studied disperse system of bimetallic Cu-Ag microparticles in the visible region; scanning electron microscopy (SEM) of the bimetallic Cu-Ag microparticles obtained; study of chemisorption of L-cysteine hydrochloride on the dispersed phase surface of bimetallic Cu-Ag microparticles; Raman-scattering spectroscopy of the sample obtained after chemisorption. [ABSTRACT FROM AUTHOR]

Objectives: Mast cell (MC) degranulation is a key process in allergic reactions and inflammatory responses. Aspartate aminotransferase 1 (AAT1)-derived endogenous sulfur dioxide (SO2) is an important regulator of MC function. However, the mechanism underlying its role in MC degranulation remains unclear. This study aimed to investigate the mechanism by which endogenous SO2 controlled MC degranulation. Methods: HMC-1 and Rat basophilic leukemia cell MC line (RBL-2H3) were used in the cell experiments. SO2 content was detected by in situ fluorescent probe. MC degranulation represented by the release rate of MC β-hexosaminidase was determined using a colorimetric assay. Sulfenylation of galectin-9 (Gal-9) in MCs and purified protein was detected using a biotin switch assay. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine the exact sulfenylation sites of Gal-9 by SO2. Animal models of passive cutaneous anaphylaxis (PCA) and hypoxia-driven pulmonary vascular remodeling were used to investigate the effect of SO2 on mast cell activation in vivo. Site-directed mutation of Gal-9 was conducted to confirm the exact site of SO2 and support the significance of SO2/Gal-9 signal axis in the regulation of MC degranulation. Results: Degranulation was increased in AAT1-knockdowned MCs, and SO2 supplementation reversed the increase in MC degranulation. Furthermore, deficiency of endogenous SO2 contributed to IgE-mediated degranulation in vitro. Besides, SO2 inhibited IgE-mediated and hypoxia-driven MC degranulation in vivo. Mechanistically, LC-MS/MS analysis and site-directed mutation results showed that SO2 sulfenylated Gal-9 at cysteine 74. Sulfenylation of the 74th cysteine of Gal-9 protein was required in the SO2-inhibited MC degranulation under both physiological and pathophysiological conditions. Conclusion: These findings elucidated that SO2 inhibited MC degranulation via sulfenylating Gal-9 under both physiological and pathophysiological conditions, which might provide a novel treatment approach for MC activation-related diseases. [ABSTRACT FROM AUTHOR]