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In this study, we developed a multiphase catalyst, BNNSs/His-Pd, by anchoring palladium nanoparticles onto L-histidine-modified boron nitride nanosheets. BNNSs/His-Pd was shown to be a good 2D heterogeneous catalyst. The enhanced affinity of the modified BNNSs for metal complexes, coupled with their inherent stability, contributes to the catalytic activity of the BNNSs/His-Pd-catalyzed Suzuki coupling reaction. The catalyst showed a broad substrate scope, good catalytic activity, and the convenience of not requiring inert gas protection in the Suzuki–Miyaura cross-coupling reaction. Even after 10 recycling cycles, the product yield remained at 95%, highlighting its significant potential for practical applications. Stable and efficient BNNSs/His-Pd heterogeneous catalysts were successfully constructed by modifying boron nitride nanosheets with L-histidine. The effect of L-histidine enhanced the dispersion and stability of Pd NPs on BNNSs carriers, combined with the inherent stability of BNNSs which resulted in the improvement of catalytic activity and recycling performance of the catalysts in the Suzuki coupling reaction. [ABSTRACT FROM AUTHOR]

Objective The effects of carnosine synthesis on the structural and microstructural determinants of meat quality have not been studied to date. Therefore, this study aimed to investigate the effect of supplementation with carnosine synthesis precursors on the characteristics and microstructure of breast muscle fibers in slow-growing Korat chickens (KR). Methods Slow-growing KR were fed a non-supplemented commercial diet (control group) or a commercial diet supplemented with 1.0% β-alanine, 0.5% L-histidine, or a combination of both 1.0% β-alanine and 0.5% L-histidine. At 10 weeks, KR were slaughtered, and the breast muscle was collected. Samples were fixed and extracted to study the microstructure, fat level, and porosity of the meat using X-ray and scanning electron microscopy, and real-time polymerase chain reaction was performed to analyze the expression of genes related to myofiber differentiation. Results L-histidine supplementation significantly altered myofiber diameter and muscle fiber density and compactness by regulating muscle fiber-type differentiation via carnosine synthase (CARNS1) and myocyte enhancer factor 2C expression, as well as myogenic differentiation antigen and myogenic regulatory factor 5 expression. While excess L-histidine potentially stimulated CARNS1 to modify muscle fiber arrangement and tenderness in breast meat, dietary β-alanine supplementation alone or in combination with L-histidine supplementation induced a relatively less remarkable but not significant (p

Densimetry is used to study the interaction between L-histidine (His) and nicotinic (NA), isonicotinic (INA), and picolinic acids (PA) in an aqueous buffer solution in the 288.15–313.15 K range of temperatures. Data on density are used to determine the apparent molar volumes and limiting apparent molar volumes of pyridine monocarboxylic acid (PyCOOH) isomers at infinite dilution, along with their temperature derivatives in a buffer solution containing the amino acid. Unlike the linear concentration dependences of the apparent molar volume of PyCOOH isomers in a buffer solution, the analogous dependences of ternary systems (PyCOOH–His–buffer) are nonlinear, indicating the formation of a molecular complex between the solutes. Limiting apparent molar expansibilities and their temperature derivatives are determined. Their values suggest that the ordering of the solvent grows in the series of isomers PA → NA → INA upon adding the amino acid to a buffer solution of PyCOOH. It is shown that the limiting apparent molar volumes of transferring PyCOOH from a buffer to a His-containing buffer solution have positive values and grow in the studied range of temperatures. The discussion of the results is based on the dominant types of molecular interactions between the solute and solvent using the Gurney model. [ABSTRACT FROM AUTHOR]

Abstract Corynebacterium glutamicum is used as an industrial platform organism for amino acid production. Previously, the organism was utilized to produce l‐histidine with research focusing on metabolic engineering approaches to increase titer and yield. Only a few studies have been published that provide information on bioprocess development, with media optimization and fed‐batch cultivation procedure being particularly promising areas. In this work, we show how experimental setups such as miniature cultivation technology, dynamic and time‐optimized LC‐MS/MS metabolic footprinting tools, and automated workflows for the detection of local and global metabolic patterns can significantly accelerate bioprocess development. Potential media bottlenecks in form of phosphate and magnesium availability were identified by sensitivity analysis in parallelized microscale cultivation assisted by lab automation. A rapid dilute‐and‐shoot flow‐injection‐analysis tandem mass spectrometry approach was used to cope with the resulting cultivation throughput and allowed to quantify amino acids with 1 min per sample. We were able to increase the l‐histidine titer of a C. glutamicum random mutagenesis mutant by a factor of 5.8 through process optimization while also identifying both known and previously unknown targets for additional strain improvements. The presented methodology can be seen as a supplement to traditional approaches in the field of bioprocess development.

In this work, L-Histidine-protected copper nanoclusters synthesized by changing the pH levels of precursor solution have been shown to display different emission wavelengths and intensities. As determined by mass spectrometry, nanoclusters Cu3L2 synthesized at acidic pH have 3 atoms in their core and emit in the greenish-yellow region, and nanoclusters Cu2L2, synthesized in the basic conditions have 2 atoms in their core and emit in the blue-green region. They are expected to have coordination through the carboxylate group and nitrogen of the imidazole ring of histidine ligand, respectively. Metal ions Mg2+, Mn2+, Zn2+, and Pb2+ selectively enhance the interaction between carboxylate – copper metal core and increase the emission intensity of Cu3L2. These metal ions weaken the interaction between imidazole nitrogen and copper metal core and quench the emission intensity of Cu2L2. As synthesized, nanoclusters exhibit good water solubility and photostability, they can act as fluorescent probes to sense the metal ions, therefore, they were utilized for the optical sensing of the mentioned metal ions. Fluorescent nanoclusters were found to sense even a very low concentration of metal ions with a limit of detection (3 σ/slope) in nanomolar range. [ABSTRACT FROM AUTHOR]

Perovskite solar cells have been proven to enhance cell characteristics by introducing passivation materials that suppress defect formation. Defect states between the electron transport layer and the absorption layer reduce electron extraction and carrier transport capabilities, leading to a significant decline in device performance and stability, as well as an increased probability of non-radiative recombination. This study proposes the use of an amino acid (L-Histidine) self-assembled monolayer material between the transport layer and the perovskite absorption layer. Surface analysis revealed that the introduction of L-Histidine improved both the uniformity and roughness of the perovskite film surface. X-ray photoelectron spectroscopic analysis showed a reduction in oxygen vacancies in the lattice and an increase in Ti4+, indicating that L-Histidine successfully passivated trap states at the perovskite and TiO2 electron transport layer interface. In terms of device performance, the introduction of L-Histidine significantly improved the fill factor (FF) because the reduction in interface defects could suppress charge accumulation and reduce device hysteresis. The FF of large-area solar modules (25 cm2) with L-Histidine increased from 55% to 73%, and the power conversion efficiency (PCE) reached 16.5%. After 500 h of aging tests, the PCE still maintained 91% of its original efficiency. This study demonstrates the significant impact of L-Histidine on transport properties and showcases its potential for application in the development of large-area perovskite module processes. [ABSTRACT FROM AUTHOR]

The amino acid L-histidine, which has an imidazole ring, was investigated as a corrosion inhibitor for AISI 1018 carbon steel in chloride solution based on the effectiveness of inhibitors containing imidazole in their composition. A neutral environment was chosen for this study due to the scarcity of research on this amino acid in this environment type. Concentrations of 250, 500, and 1000 ppm were evaluated. Various methods were used to determine inhibition effectiveness, including mass loss, open circuit potential, linear potentiodynamic polarization, and electrochemical impedance spectroscopy. For mass loss, the inhibition efficiency varied from 83 to 88% according to the increase in concentration. For the electrochemical tests, the efficiency variation ranged from 62 to 90% with increasing amino acid concentration. Furthermore, a simulation analysis using quantum chemical calculations within the scope of Density Functional Theory (DFT) revealed that histidine's nucleophilic character is crucial for its corrosion inhibitory capacity in an aqueous medium at pH 7. The inhibition efficiency increased with increasing concentration in a neutral medium, following the Langmuir isotherm for the adsorption of L-histidine. Additional studies were carried out using Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TGA). Analysis of the substrate surface by scanning electron microscopy (SEM) showed greater preservation with the addition of L-histidine, confirming its adsorption on the steel. Atomic Force Microscopy (AFM) also demonstrated an improvement in surface roughness in the presence of amino acids compared to the medium without an inhibitor. [ABSTRACT FROM AUTHOR]

The analysis of dietary supplements is far less regulated than pharmaceuticals, leading to potential quality issues. Considering their positive effect, many athletes consume supplements containing l-histidine and β-alanine. A new microfluidic method for the determination of l-histidine and β-alanine in dietary supplement formulations has been developed. For the first time, capacitively coupled contactless conductivity detection was employed for the microchip electrophoresis of amino acids in real samples. A linear relationship between detector response and concentration was observed in the range of 10–100 µmol L–1 for l-histidine (R2 = 0.9968) and β-alanine (R2 = 0.9954), while achieved limits of detection (3 × S/N ratio) were 4.2 µmol L–1 and 5.2 µmol L–1, respectively. The accuracy of the method was confirmed using recovery experiments as well as CE-UV-VIS and HPLC-UV-VIS techniques. The developed method allows unambiguous identification of amino acids in native form without chemical derivatization and with the possibility of simultaneous analysis of amino acids with metal cations. [ABSTRACT FROM AUTHOR]

In this study, Cu2+ modulated silver nanoclusters were constructed for the turn-on, label-free detection of L-histidine. Six Ag NCs protected by oligonucleotides (DNA-Ag NCs) were tested in a series of experiments. Finally, A-DAN-Ag NCs were chosen as the best candidate due to their excellent fluorescent properties. The fluorescence of A-DAN-Ag NCs was quenched using Cu2+ through energy or electron transfer. However, quenched fluorescence could be restored dramatically in the presence of L-histidine due to Cu2+ liberation from A-DAN-Ag NCs and because of the chelation between the imidazole group of L-histidine and Cu2+. The proposed sensor exhibited high selectivity towards L-histidine over other amino acids, with a limit of detection (LOD) of 0.096 μM ranging from 0 to 8 μM. The proposed sensor succeeded in detecting L-histidine in diluted human urine. Therefore, the sensor has promising practical applications in biological systems. [ABSTRACT FROM AUTHOR]

Simple Summary: Ketosis in cows occurs when excessive ketone bodies are produced by the liver, typically due to energy deficits from reduced feed intake or specific dietary conditions. Scientists have noticed that cows with ketosis have lower amounts of a substance named L-histidine. This sparked curiosity about how L-histidine might help cows with this problem. To understand this better, researchers looked at changes in cow mammary cells caused by the fat and whether L-histidine could help. They found many changes in the cell's substances, some increasing and some decreasing, showing that the cells were trying to respond to the fat. Interestingly, when L-histidine was added, it seemed to help by changing some of these substances, suggesting it might protect the cells. One particular substance seemed to play a big role and was affected by both the fat and L-histidine in different ways. This research helps us understand the complicated ways cow cells react to excess fat and suggests that L-histidine could be a helpful tool in keeping cows healthy, which is valuable for farmers and the dairy industry. Non-esterified fatty acids (NEFAs) are pivotal in energy metabolism, yet high concentrations can lead to ketosis, a common metabolic disorder in cattle. Our laboratory observed lower levels of L-histidine in cattle suffering from ketosis, indicating a potential interaction between L-histidine and NEFA metabolism. This relationship prompted us to investigate the metabolomic alterations in bovine mammary epithelial cells (BMECs) induced by elevated NEFA levels and to explore L-histidine's potential mitigating effects. Our untargeted metabolomic analysis revealed 893 and 160 metabolite changes in positive and negative models, respectively, with VIP scores greater than 1 and p-values below 0.05. Notable metabolites like 9,10-epoxy-12-octadecenoic acid were upregulated, while 9-Ethylguanine was downregulated. A pathway analysis suggested disruptions in fatty acid and steroid biosynthesis pathways. Furthermore, L-histidine treatment altered 61 metabolites in the positive model and 34 in the negative model, with implications for similar pathways affected by NEFA. Overlaying differential metabolites from both conditions uncovered a potential key mediator, 1-Linoleoylglycerophosphocholine, which was regulated in opposite directions by NEFA and L-histidine. Our study uncovered that both NEFA L- and histidine metabolomics analyses pinpoint similar lipid biosynthesis pathways, with 1-Linoleoylglycerophosphocholine emerging as a potential key metabolite mediating their interaction, a discovery that may offer insights for therapeutic strategies in metabolic diseases. [ABSTRACT FROM AUTHOR]

ABSTRACT: Carnosine is a physiologically important molecule in normal human body functions. Chicken meat is an excellent source of carnosine; especially slow-growing Korat chicken (KR) females have a high carnosine content in their meat. The carnosine content of chicken meat can be increased by dietary supplementation of β-alanine (βA) and L-histidine (L-His). Our objective was to reveal the pathways and genes through jejunal transcriptomic profiling related to βA and L-His absorption and transportation. We collected whole jejunum samples from 5 control and 5 experimental KR chicken, fed with 1% βA and 0.5% L-His supplementation. A total of 407 differentially expressed genes (P < 0.05, log2 fold change ≥2) were identified, 272 of which were down-regulated and 135 up-regulated in the group with dietary supplementation compared to the control group. Based on the integrated analysis of the protein–protein interaction network and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway maps, 87 gene ontology terms were identified and 6 KEGG pathways were significantly (P < 0.05) enriched in the jejunum. The analyses revealed 6 key genes, KCND3, OPRM1, CCK, GCG, TRH, and GABBR2, that are related to neuroactive ligand-receptor interaction and the calcium signaling pathway. These findings give insight regarding the molecular mechanism related to carnosine precursor absorption and transportation in the jejunum and help to identify useful molecular markers for improving the carnosine content in slow-growing KR chicken meat.

Obesity stands as a pervasive and significant global health issue, with a lack of definitive and curative therapeutic solutions currently available. Here we studied the synergetic ameliorating effect of coupled administration of GABA agonist; baclofen with histidine against the high fat (HFD) induced lipotoxicity in experimentally obese rats. Animals were divided into six groups. The control group (group 1) was fed a basal diet. Obesity was induced in groups 2 to 6 by HFD for 60 days and concomitantly treated with distilled water or Fluoxetine or Baclofen or L-Histidine or a half-dose combination of Bac plus His, respectively. HFD leads to aberrations in neuronal function, affecting neurotransmitters such as monoamines, turnover rates, and levels of excitatory and inhibitory amino acids when compared to control (P < 0.05). Additionally, it induces notable cellular oxidative stress and energy homeostasis distortion. Simultaneous dysregulation of genes associated with glucose sensing and availability was observed, characterized by a notable decrease in the expression of the glycogen phosphorylase gene and a marked increase in the expression of glucokinase and proglucagon genes (P < 0.05). Both Bac and His single dosing rectified the HDF-induced alterations in 5HT, DA and NE neurotransmitters with their metabolites 5HIAA, DOPAC and HVA, together with Nrf1 and NF-KB1 inflammatory markers and partially quenched the HDF-induced increase in the level of MDA and 8OHdG oxidative stress byproducts, and restored the activity of GSH and SOD antioxidant enzymes. Remarkably, the combined administration of Bac and His at half-dose exhibited significant behavioral improvement, fully normalizing neurochemical and cellular energy homeostasis, and restoring cellular redox and inflammatory parameters to control values following HFD-induced cellular insult. In conclusion, the combined half-dosing of Bac plus His treatment exhibited substantial improvements in behavior and fully normalized neurochemical and cellular parameters, offering a promising approach for addressing obesity-related complexities.

To explore the effects of dietary histidine on growth, non-specific immune and ovarian development of red swamp crayfish (Procambarus clarkii), crayfish (5.98 ± 0.11 g) were fed six isoproteic and isoenergetic diets with histidine levels (3.90 (control), 5.67, 8.42, 10.57, 12.32, and 15.02 g/kg) for eight weeks. The results showed that nearly all tested indicators demonstrated significant linear or quadratic trends with the variation of histidine levels. Weight gain rate (WGR), feed conversion ratio (FCR), protein efficiency rate (PER), protein deposition rate (PDR), and essential amino acid deposition rates obtained the optimal values when the dietary histidine level was 8.42 g/kg or 10.57 g/kg. Compared to the control group, the 8.42 g/kg group exhibited enhanced nonspecific immunity and antioxidant properties, and the 10.57 g/kg group demonstrated significant increase in the frequency of B cells in the hepatopancreas, the length and width of intestinal villi and the activities of protease and lipase. Additionally, the 10.57 g/kg group showed elevated ecdysterone hormone, gonadal index (GI), cAMP content and the relative abundance of beneficial intestinal microbiota. The mRNA expressions of MIH, ECR, RXR, chitinase, PKA, fox L2, Vg, cdc2, and cyclin B genes were also significantly modulated by dietary histidine levels. Overall, dietary histidine improved the intestinal health and regulated the immune function to enhance protein utilization and promote growth performance of red swamp crayfish. In addition, dietary histidine improved the synthesis of yolk substance, promoted the development of ovarian cells, and then improved the ovarian index of female crayfish. Based on the quadratic curve regression model analysis of the relationship between WGR, SGR, PDR, PER, FCR, GI and dietary histidine level, the optimal histidine level was 9.36–10.91 g/kg (dry matter), corresponding to 26.63–31.04 g/kg of dietary protein in red swamp crayfish.

The amino acid L-histidine, which has an imidazole ring, was investigated as a corrosion inhibitor for AISI 1018 carbon steel in chloride solution based on the effectiveness of inhibitors containing imidazole in their composition. A neutral environment was chosen for this study due to the scarcity of research on this amino acid in this environment type. Concentrations of 250, 500, and 1000 ppm were evaluated. Various methods were used to determine inhibition effectiveness, including mass loss, open circuit potential, linear potentiodynamic polarization, and electrochemical impedance spectroscopy. For mass loss, the inhibition efficiency varied from 83 to 88% according to the increase in concentration. For the electrochemical tests, the efficiency variation ranged from 62 to 90% with increasing amino acid concentration. Furthermore, a simulation analysis using quantum chemical calculations within the scope of Density Functional Theory (DFT) revealed that histidine’s nucleophilic character is crucial for its corrosion inhibitory capacity in an aqueous medium at pH 7. The inhibition efficiency increased with increasing concentration in a neutral medium, following the Langmuir isotherm for the adsorption of L-histidine. Additional studies were carried out using Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TGA). Analysis of the substrate surface by scanning electron microscopy (SEM) showed greater preservation with the addition of L-histidine, confirming its adsorption on the steel. Atomic Force Microscopy (AFM) also demonstrated an improvement in surface roughness in the presence of amino acids compared to the medium without an inhibitor.

Background and purpose: In this study, we examined the impact of Zn-bioMOF structures on the physical and chemical characteristics as well as the in vitro biocompatibility of a matrix composed of semi-interpenetrating polymeric networks (semi-IPN) made from collagen and L-tyrosine-based polyelectro­lytes. Experimental approach: We hydrothermally synthesized L-1, ZIF-8H Zn-bioMOFs, and the Zn-(L-His)2 complex, utilizing L-histidine, a bioactive amino acid, as a ligand. These metal-organic compounds primarily enhance the mechanical properties of the novel composite hydrogels through physical interactions such as hydrogen bonds and dipolar interactions. They also accelerate the gelation process. Composites containing Zn-bioMOFs exhibited greater biocompatibility than the collagen/poly­electrolyte matrix alone, as evidenced by cytotoxicity assays conducted with porcine fibroblasts, human monocytes, and RAW 264.7 cells. Further­more, the evaluated materials did not exhibit hemolysis. We investigated the influence of Zn-bioMOFs on cell signaling by measuring the levels of crucial cytokines involved in the healing process, such as MCP-1, TGF-β, IL-10, and TNF-α secreted by human monocytes. Key results: The composite with Zn(L-His)2 promoted the secretion of MCP-1, TGF-β, and IL-10, while a decrease in TNF-α secretion was observed with the composite containing ZIF-8H. Zn-bioMOFs enhanced certain aspects of the biomedical and physicochemical properties of the composite hydrogels. Conclusion: Although the overall performance of the tested materials did not differ significantly, it is worth noting that the presence of Zn-bioMOFs in biopolymeric hydrogels modulated the metabolic activity of cells important for healing and their cytokine signaling, leading to improved biomedical performance.

ABSTRACT: The slow-growing Korat chicken (KR) has been developed to provide an alternative breed for smallholder farmers in Thailand. Carnosine enrichment in the meat can distinguish KR from other chicken breeds. Therefore, our aim was to investigate the effect of enriched carnosine synthesis, obtained by the β-alanine and L-histidine precursor supplementation in the diet, on changes to metabolomic profiles and biochemical compounds in slow-growing KR jejunum tissue. Four hundred 21-day-old female KR chickens were divided into 4 experimental groups: a group with a basal diet, a group with a basal diet supplemented with 1.0% β-alanine, 0.5% L-histidine, and a mix of 1.0% β-alanine and 0.5% L-histidine. The feeding trial lasted 70 d. Ten randomly selected chickens from each group were slaughtered. Metabolic profiles were analyzed using proton nuclear magnetic resonance spectroscopy. In total, 28 metabolites were identified. Significant changes in the concentrations of these metabolites were detected between the groups. Partial least squares discriminant analysis was used to distinguish the metabolites between the experimental groups. Based on the discovered metabolites, 34 potential metabolic pathways showed differentiation between groups, and 8 pathways (with impact values higher than 0.05, P < 0.05, and FDR < 0.05) were affected by metabolite content. In addition, biochemical changes were monitored using synchrotron radiation-based Fourier transform infrared microspectroscopy. Supplementation of β-alanine alone in the diet increased the β-sheets and decreased the α-helix content in the amide I region, and supplementation of L-histidine alone in the diet also increased the β-sheets. Furthermore, the relationship between metabolite contents and biochemical compounds were confirmed using principal component analysis (PCA). Results from the PCA indicated that β-alanine and L-histidine precursor group was highly positively correlated with amide I, amide II, creatine, tyrosine, valine, isoleucine, and aspartate. These findings can help to understand the relationships and patterns between the spectral and metabolic processes related to carnosine synthesis.

Background: In contrast to modern rational metabolic engineering, classical strain development strongly relies on random mutagenesis and screening for the desired production phenotype. Nowadays, with the availability of biosensor-based FACS screening strategies, these random approaches are coming back into fashion. In this study, we employ this technology in combination with comparative genome analyses to identify novel mutations contributing to product formation in the genome of a Corynebacterium glutamicuml-histidine producer. Since all known genetic targets contributing to l-histidine production have been already rationally engineered in this strain, identification of novel beneficial mutations can be regarded as challenging, as they might not be intuitively linkable to l-histidine biosynthesis. Results: In order to identify 100 improved strain variants that had each arisen independently, we performed > 600 chemical mutagenesis experiments, > 200 biosensor-based FACS screenings, isolated > 50,000 variants with increased fluorescence, and characterized > 4500 variants with regard to biomass formation and l-histidine production. Based on comparative genome analyses of these 100 variants accumulating 10–80% more l-histidine, we discovered several beneficial mutations. Combination of selected genetic modifications allowed for the construction of a strain variant characterized by a doubled l-histidine titer (29 mM) and product yield (0.13 C-mol C-mol−1) in comparison to the starting variant. Conclusions: This study may serve as a blueprint for the identification of novel beneficial mutations in microbial producers in a more systematic manner. This way, also previously unexplored genes or genes with previously unknown contribution to the respective production phenotype can be identified. We believe that this technology has a great potential to push industrial production strains towards maximum performance. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of the process of stabilization of zinc silicate nanoparticles using the amino acid L-histidine. Zinc acetate was used as a precursor, sodium silicate was used as a precipitant, and the amino acid L -histidine acted as a stabilizer. Synthesis was carried out by chemical precipitation in an aqueous medium. A simultaneous thermal analysis was carried out, as a result of which it was found that the addition of an amino acid to nanosized zinc silicate has a great influence on the crystal structure and thermal transitions for this material. Next, the X-ray phase analysis was carried out, which showed that of zinc silicate particles have an amorphous structure and are in a nanoscale state. At the next stage of the work, the process of interaction of an amino acid with a zinc silicate particle was studied by IR spectroscopy. The results of the study showed that stabilization of particles is accompanied by the formation of a chemical bond between silicon in the zinc silicate molecule and the amino group in the L -histidine molecule.

Abstract L-Histidine immobilized montmorillonite is prepared and used as an adsorbent for removal of As(III) from aqueous solutions. The L-Histidine immobilized montmorillonite is characterized by FTIR, XRD, TGA and PZC techniques that confirmed the successful insertion of Histidine into interlayer of montmorillonite structure. The various parameters such as pH, reaction time, temperature, concentration of As(III) and adsorbent dosage are optimized to obtain maximum As(III) adsorption. It is observed that usually the removal of As(III) is increased with increasing the amount of adsorbent, contact time, temperature and till pH 6. The results showed that all these adsorption parameters greatly influenced the adsorption process. The various adsorption isotherm models including Langmuir, Freundlich, Temkin and Dubinin-Radishkevich (DR) as well as kinetics models are applied to the adsorption data. The Langmuir isotherm and pseudo-second order kinetics model are well-fitted to the adsorption data. Further, the probability distribution function (PDF) is applied that verified the adsorption data well while the Akaike’s Information Criterion (AICcorrected) and Absolute Average Relative Deviation (AARD) statistical models supported the best fit adsorption isotherms. The PDF model have provided a good statistical identification of adsorption parameters, adsorption rates and maxima whereas AICcorrected and AARD models revealed the well-fitting of Langmuir adsorption isotherm model in correlating the equilibrium data. Thermodynamic parameters (ΔH, ΔS, ΔG) proved the endothermic and spontaneous nature of adsorption process along with entropical changes occurring at solid-solution interface. The results showed that L-Histidine immobilized montmorillonite is an excellent material for As(III) adsorption with maximum adsorption capacity of 87.7 mg g−1.

L-Histidine (C6H9N3O2), one of the most prominent positively charged amino acids, has shown a lot of potential as a future molecular device. A subcomponent of proteins, L-Histidine has been acknowledged for its applications in designing future switching devices and logic gates. Interpreting its transport parameters while aligning it as a central molecule with a series of metallic electrodes using a self-consistent function and implementing the density functional theory and non-equilibrium Green's function (NEGF-DFT) approach for our computational analysis, we observe that the proposed devices exhibit dissimilar rectification ratios (RR), besides demonstrating negative differential resistance (NDR) regimes. The RRs of DFT-D3 corrected and the uncorrected molecular device is also compared to verify the impact of van der Waals (vdW)-type interaction on current–voltage characteristics. The molecular device with copper electrodes yields the maximum rectification ratio of 8.1, while the device with palladium electrodes yields the highest peak-to-valley current ratio of 1.28. Such a study proffers the idea of choosing proper electrodes for exploring the rectification ratio of biomolecules. Moreover, using these L-Histidine-based molecular devices, we have proposed AND Logic gate and OR Logic gate, which can pave the way to an alternate research area of using peptides as future molecular devices. [ABSTRACT FROM AUTHOR]

For the first time AFM (atomic-force microscopy) was used to record significant changes in the geometric parameters of the image of erythrocytes in vitro under conditions of glycolytic starvation (ATP (Adenosine triphosphate) deficiency). The difference in the action of antioxidants, phenosan K, and Ihfan-10 on erythrocytes that we detected with AFM seems to be mainly due to their difference in hydrophobicity. We used the AFM method to research the self-organization of the components of the active center of P450 (Porphyrin-450) metalloenzymes that are part of a class of hemoproteins with functions of affinity to molecular oxygen O2. Stable supramolecular nanostructures in the form of triangular prisms based on the iron porphyrin complex with amino acids due to self-assembly involving intermolecular hydrogen bonds were received. A possible scheme for the formation of such structures is proposed. [ABSTRACT FROM AUTHOR]

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A new three metal complexes of La(III), Ce(IV) and UO2(II) ions have been synthesized based on a Schiff base derived from the condensation of L-histidine and anisaldehyde. All prepared compounds were characterized by different spectroscopic techniques and Density-functional theory (DFT) calculations. The complexes were proposed to have an octahedral structure based on the investigated results. The optimized shape, numbering system, and dipole moment vector of Ligand and La, Ce, and UO2 (1:1) chelates were investigated. The Schiff base ligand and complexes exhibit moderate action against all of the bacteria tested, with P. aeruginosa, Klebsiella sp., and E. faecalis respectively being the order of inhibition. [ABSTRACT FROM AUTHOR]

The adsorption isotherms of L-histidine on MKN-SWCNT-S1 CNTs from aqueous solution at temperatures of 25, 35, 45, 55, 65 and 80 °C were interpreted within the framework of the single-layer cluster adsorption model. A new approach to determine the equilibrium parameters of the cluster adsorption isotherm equation and sorbate structure on CNTs, as well as a nonlinear modelling method, was applied. To confirm the cluster nature of amino acid adsorption on CNTs, the clustering criterion proposed in the previous work was applied, and the cluster structure was evaluated, which is significant for the application of CNTs in biomedicine. The found equilibrium parameters of adsorption were applied to the determination of thermodynamic characteristics of adsorption (changes in Gibbs energy, enthalpy and entropy) of L-histidine on CNTs and the character of adsorption was analysed. [Display omitted] • The adsorption isotherms of L-histidine on CNTs were interpreted within the framework of the cluster adsorption model. • The cluster character of L-histidine adsorption on CNTs was proved. • The parameters of adsorption isotherms and the structure of histidine clusters on CNTs were determined. • The linearisation method was applied to determine the parameters of adsorption isotherms. • The found isotherms parameters were applied to the determination of thermodynamic characteristics of adsorption. [ABSTRACT FROM AUTHOR]

Summary: In this study, the effect of several additives, including CaCl2, L‐histidine (L‐His) and sodium pyrophosphate, incorporation with ultrasound treatment on the gel properties of reduced‐salt surimi, was tested. Among these additives and ultrasound treatment times, 0.1% L‐His and 10‐min ultrasound alone were determined to be more effective in increasing the gel strength, water‐holding capacity (WHC) and reducing cooking loss (CL) of reduced‐salt (1% NaCl) surimi gel. L‐His and ultrasound alone or in combination could facilitate the transition of α‐helix to β‐sheet and random coil, thereby increasing hydrophobic interactions and disulfide bonds in the gel. The results of low‐field nuclear magnetic resonance showed that the proportion of immobilised water (PT22) in reduced‐salt surimi gel was significantly increased (P < 0.05). The storage modulus (G′) of reduced‐salt surimi gel was also increased. Moreover, scanning electron microscopy results showed that the gels treated with L‐His and ultrasound alone or in combination had a more compact network structure. Notably, the synergy of L‐His combined ultrasound treatment was the most effective in enhancing the characteristics of reduced‐salt surimi gel. [ABSTRACT FROM AUTHOR]

The heat‐induced gelation of actomyosin plays a key role in meat processing. Our previous study showed that L‐histidine could affect the characteristics of a heat‐induced gel of myosin on a low ionic strength. To apply the specific effect of L‐histidine to meat processing, the heat‐induced gel properties of actomyosin in the presence of L‐histidine were investigated. Actomyosin in a low ionic strength solution containing L‐histidine did not form a gel upon heating. The dynamic rheological properties of actomyosin in low ionic strength solutions were distinct depending on the presence or absence of L‐histidine. Electron microscopy showed that, heated at 50°C, actomyosin in a low ionic strength solution containing L‐histidine remained a filamentous structure. The surface hydrophobicity of actomyosin was stable up to 50°C in a low ionic strength solution containing L‐histidine. In conclusion, L‐histidine might suppress the aggregation of actomyosin and inhibit heat‐induced gelation in a low ionic strength solution. [ABSTRACT FROM AUTHOR]

L-Histidine immobilized montmorillonite is prepared and used as an adsorbent for removal of As(III) from aqueous solutions. The L-Histidine immobilized montmorillonite is characterized by FTIR, XRD, TGA and PZC techniques that confirmed the successful insertion of Histidine into interlayer of montmorillonite structure. The various parameters such as pH, reaction time, temperature, concentration of As(III) and adsorbent dosage are optimized to obtain maximum As(III) adsorption. It is observed that usually the removal of As(III) is increased with increasing the amount of adsorbent, contact time, temperature and till pH 6. The results showed that all these adsorption parameters greatly influenced the adsorption process. The various adsorption isotherm models including Langmuir, Freundlich, Temkin and Dubinin-Radishkevich (DR) as well as kinetics models are applied to the adsorption data. The Langmuir isotherm and pseudo-second order kinetics model are well-fitted to the adsorption data. Further, the probability distribution function (PDF) is applied that verified the adsorption data well while the Akaike's Information Criterion (AICcorrected) and Absolute Average Relative Deviation (AARD) statistical models supported the best fit adsorption isotherms. The PDF model have provided a good statistical identification of adsorption parameters, adsorption rates and maxima whereas AICcorrected and AARD models revealed the well-fitting of Langmuir adsorption isotherm model in correlating the equilibrium data. Thermodynamic parameters (ΔH, ΔS, ΔG) proved the endothermic and spontaneous nature of adsorption process along with entropical changes occurring at solid-solution interface. The results showed that L-Histidine immobilized montmorillonite is an excellent material for As(III) adsorption with maximum adsorption capacity of 87.7 mg g−1. [ABSTRACT FROM AUTHOR]

Soil salinization is an important worldwide environmental problem and the main reason to reduce agricultural productivity. Recent findings suggested that histidine is a crucial residue that influences the ROS reduction and improves the plants’ tolerance to salt stress. Herein, we conducted experiments to understand the underlying regulatory effects of histidine on maize root system under salt stress (100 mM NaCl solution system). Several antioxidant enzymes were determined. The related expressed genes (DEGs) with its pathways were observed by Transcriptome technologies. The results of the present study confirmed that histidine can ameliorate the adverse effects of salt stress on maize root growth. When the maize roots exposed to 100 mM NaCl were treated with histidine, the accumulation of superoxide anion radicals, hydrogen peroxide, and malondialdehyde, and the content of nitrate nitrogen and ammonium nitrogen were significantly reduced; while the activities of superoxide dismutase, peroxidase, catalase, nitrate reductase, glutamine synthetase, and glutamate synthase were significantly increased. Transcriptome analysis revealed that a total of 454 (65 up-regulated and 389 down-regulated) and 348 (293 up-regulated and 55 down-regulated) DEGs were observed when the roots under salt stress were treated with histidine for 12 h and 24 h, respectively. The pathways analysis of those DEGs showed that a small number of down-regulated genes were enriched in phytohormone signaling and phenylpropanoid biosynthesis at 12 h after histidine treatment, and the DEGs involved in the phytohormone signaling, glycolysis, and nitrogen metabolism were significantly enriched at 24 h after treatment. These results of gene expression and enzyme activities suggested that histidine can improve the salt tolerance of maize roots by enriching some DEGs involved in plant hormone signal transduction, glycolysis, and nitrogen metabolism pathways. [ABSTRACT FROM AUTHOR]

Herein, we have successfully prepared self-doped carbon dots with nitrogen elements (NCD) in a simple one-pot hydrothermal carbonization method, using L-histidine as a new precursor. The effect of as-prepared carbon dots was studied for photoelectrochemical (PEC) water splitting by decorating NCDs upon TiO2 nanorods systematically by changing the loading time from 2 h to 8 h (TiO2@NCD2h, TiO2@NCD4h, TiO2@NCD6h, and TiO2@NCD8h). The successful decorating of NCDs on TiO2 was confirmed by FE-TEM and Raman spectroscopy. The TiO2@NCD4h has shown a photocurrent density of 2.51 mA.cm−2, 3.4 times higher than the pristine TiO2. Moreover, TiO2@NCD4h exhibited 12% higher applied bias photon-to-current efficiency (ABPE) than the pristine TiO2. The detailed IPCE, Mott–Schottky, and impedance (EIS) analyses have revealed the enhanced light harvesting property, free carrier concentration, charge separation, and transportation upon introduction of the NCDs on TiO2. The obtained results clearly portray the key role of NCDs in improving the PEC performance, providing a new insight into the development of highly competent TiO2 and NCDs based photoanodes for PEC water splitting. [ABSTRACT FROM AUTHOR]

The interaction of Pr(III) with L-Histidine has been analysed through 4f-4f transition spectra in different solvents. Mode of binding of Pr(III) with L-Histidine is interpreted considering the variations in evaluated values of intensity parameters like oscillator strength (P) and Judd Ofelt electric dipole intensity parameters ‘Tλ’ (λ = 2,4,6). Energy interaction parameters like Slater–Condon (Fk's), Lande factor (ξ4f), Racah energy (Ek), nephelauxetic effect (β), bonding (b1/2) and percent covalency (δ). It is further studied through kinetics, subsequently activation energy (Ea), pre-exponential factor (A), specific rate constant/rate constant (k) and thermodynamic parameters viz, ΔH°, ΔG°, ΔS° etc., has been evaluated from which detailed thermodynamical information for the complexation of Pr(III) with L-Histidine in DMF solvent can be explored. Solution spectral studies through kinetic approach could provide pertinent information about the mechanism, reaction pathways, and also about the mode of chemical bond.

With the widespread application of nuclear technologies, radiation dose measurement is important. Ferrous sulfate dosimeters are common chemical dosimeters, but their high detection limit and narrow dosimetry range limit their application in some fields. In this work, we introduce a novel dosimetry approach for ferrous sulfate dosimeters utilizing the fluorescence properties of gold nanoclusters (AuNCs) capped with histidine. The Fe2+ ions in the ferrous sulfate dosimeter are oxidized to Fe3+ ions during irradiation. The presence of Fe3+ ions results in the fluorescence quenching of AuNCs, establishing a correlation between the fluorescence intensity of the dosimeter and irradiation doses. The lowest detection limit of the fluorescence dosimeter was found to be 2 Gy. Moreover, the dose response of the dosimeter showed good linearity within the dose range of 2–400 Gy. The dosimetric sensitivity of the fluorescence dosimeter was 17.9% higher than that of ultraviolet–visible spectroscopy. The results indicate that the dosimetry method utilizing the fluorescence properties of AuNCs significantly improves the detection sensitivity and detection limit of the dosimeter. Our work provides a new dosimetry method for ferrous sulfate dosimeters that can be used in a wider range of irradiation situations. • Fluorescent probes are prepared utilizing nontoxic histidine as ligands. • The lowest detection limit of dosimeters is 2 Gy based on fluorescence dosimetry. • The fluorescence intensity of dosimeters is linear with radiation doses (2–400 Gy). • The detection sensitivity of fluorescence dosimeters improves by 17.9%. [ABSTRACT FROM AUTHOR]

Adsorption isotherms are obtained for L-histidine on carbon nanotubes using aqueous solutions at temperatures of 25, 35, 45, 55, 65, and 80°C. The isotherms are interpreted by using the cluster adsorption model and analyzing the dependence of the strength of the bond nanotube–amino acid on temperature. Equations of the adsorption isotherms are obtained for all temperatures. The calculated results indicate that L-histidine is fixed on a nanotube's surface in the form of monomers and different clusters. The equilibrium characteristics of adsorption are found to change as the temperature rises. Values obtained for the coefficients of equilibrium are used to calculate apparent enthalpy ΔH* of L-histidine adsorption by nanotubes, according to the van't Hoff equation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Improved mechanistic understanding of the interactions in aqueous protein solutions. • Rapid and resource-efficient identification of potential excipient mixtures by methodical selection. • Correlation between charge & side chain length of the amino acid and the respective influence on the protein stability. • Ratio/molalities of excipients as decisive factor in design of aqueous protein formulations. • Potential of transferability of excipient mixture choice to different proteins. Still today, high-concentration protein formulations are often developed based on high-throughput experimental screening approaches. Although likely delivering working formulations, these approaches do not lead to a deep/mechanistic understanding of the protein phase behavior in solution. Within this work, we thus optimized and enhanced a recent approach for an initial low effort selection of potential excipients and excipient mixtures to be used in high-concentration protein formulations. This approach considers both: molecular interactions and thermodynamic determinants to access the phase behavior of the proteins in solution, as well as pharmaceutical engineering boundaries (such as osmotic pressure and osmolality) to deliver on optimal formulation conditions. Water activity coefficient γ W -calculations (used to describe the protein environment in solution), unfolding temperature (conformational stability) and protein-protein interactions (colloidal stability) are used as determinants. Amino acids (20 proteinogenic amino acids), selected amino acid mixtures, as well as mixtures of amino acids and trehalose (l -arginine-trehalose; l -histidine-trehalose) are considered as model excipients. The approach is extends by studying the long-term stability of the predicted formulation conditions for a γ-globulin from human blood and denosumab. The results reveal, that by combining protein-specific experiments as well as model-based studies for the selection of excipient mixtures in high concentration protein formulations, the effort as well as the resource requirements can be reduced significantly. [ABSTRACT FROM AUTHOR]

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This work describes the synthesis of sebacic acid capped silver nanoparticles (SA-AgNPs) by the wet chemical method for the detection of l-Histidine in blood serum and urine samples. The synthesized SA-AgNPs were characterized by several techniques. The obtained particles were spherical in shape and the average diameter was calculated by HR-TEM images to be 11 nm. Moreover, the synthesized SA-AgNPs were stable for more than 3 months in solution. The synthesized SA-AgNPs showed the surface plasmon resonance (SPR) band at 420 nm. Interestingly, after the addition of 18.1 μM of l-Histidine into the SA-AgNPs solution, the SPR band absorbance decreased and the colour of the solution changed from brown to colourless. Based on the changes in the SPR band, we calculated the lowest detection limit to be 122 nM. The observed colour shift and spectral changes were due to the aggregation of SA-AgNPs induced by l-Histidine via hydrogen bonding interaction. Additionally, a possible mechanism is discussed. Furthermore, a 268-fold excess of common interferences did not interfere with the detection of 18.1 μM of l-Histidine. We successfully applied the SA-AgNPs probe for the detection of l-Histidine in blood serum and urine samples. Further, we validated our system with the HPLC technique. Importantly, we prepared a portable smartphone aided paper-based kit for on-site monitoring of l-Histidine. We strongly hope that this facile synthesis of SA-AgNPs and the portable paper-based kit will represent a step forward in the field of biosensing and materials science.

Complex formation in the ternary systems copper(II)/nickel(II)/cobalt(II) – isonicotinic acid hydrazide – L-histidine was studied by the methods of spectrophotometry and mathematical modeling in an aqueous solution with 0.1 mol dm–3 KNO3 as a background electrolyte. The compositions, formation constants, and spectral parameters of the heteroligand complexes with a metal/hydrazide/amino acid ratio of 1:1:1 were determined. It was found that the heteroligand complexes with the neutral form of isonicotinic acid hydrazide have higher stability values than those with the protonated form. The stability of bis- and tris-complexes of the same composition in the series copper(II) – nickel(II) – cobalt(II) is in agreement with the Irving–Williams order. Three isomers of the heteroligand complex of nickel(II) with the protonated form of isonicotinic acid hydrazide and histidine zwitterion were optimized by the method of molecular mechanics. In the system with cobalt(II), a reversible interaction with atmospheric oxygen was revealed.

In this research, a new multilayered magnetized bio-nanocomposite has been prepared. At first, the amino acid-based ionic liquid was obtained from L-histidine and trichloroacetic acid (L–His+CCl3CO2−), embedded on the polyethylene glycol-functionalized silicated-nanomagnetite, to prepare the final nanostructure (L–His+CCl3CO2−@PEG@SiO2-nano Fe3O4). The bio-nanocomposite was characterized by several techniques such as FT-IR, FESEM, TGA/DTG, EDAX, TEM, VSM, and XRD. The catalytic activity of the core–shell nanostructure was examined in one-pot three-component reaction between aryl aldehydes, indoles, and β-naphthol/phenols to get some new 3-(α,α-diarylmethyl)indoles under solvent-free conditions at 75 °C. Eco-friendly protocol in the absence of hazardous solvents, no observation of by-products such as bis(indolyl)methanes (BIMs), in addition to recovery and reusability of the nanostructure within 3 runs without activity loss are some highlighted notable features of the work. The reused bio-nanocomposite was also characterized through FESEM technique. [ABSTRACT FROM AUTHOR]

This study aimed to analyze and discuss the biomarkers of PEGylated liposomal doxorubicin (PLD) injection-induced hypersensitivity reactions (HSRs) in advanced breast cancer patients. Fourteen patients from Sun Yat-sen Memorial Hospital were included in the study between April 15th, 2020 and April 14th, 2021. Patient plasma was collected 30 min before PLD injection. HSRs were found to occur in a total of 9 patients (64.3%). No association was found between HSRs and various patient characteristics such as age, body surface area, anthracycline treatment history, IgE, and complement 3 and 4 (p > 0.05). Non-targeted metabolomics analysis of patient plasma was performed, and several metabolites showed significant association with HSRs. In particular, l-histidine (fold change = 91.5, p = 0.01) showed significantly higher levels in the immediate HSR group, while myristicin (fold change = 0.218, p = 0.003), urocanic acid (fold change = 0.193, p = 0.007), and d-aldose (fold change = 0.343, p = 0.003) showed significantly lower levels in the same group. In vivo experiments showed that exogenous histidine aggravated HSRs and increased IgE plasma levels in rats following the injection of PLD. Histidine can be decarboxylated to histamine by histidine decarboxylase. Histidine decarboxylase inhibitor 4-bromo-3-hydroxybenzoic acid improved symptoms and IgE levels in vivo. These findings suggested that l-histidine can be a potential biomarker for PLD-induced HSR. Moreover, an antihistamine drug, histidine decarboxylase inhibitor, or dietary histidine management could be used as potential preventive measures. Furthermore, metabolomics research could serve as a powerful method to explore biomarkers or uncover mechanisms of drug side effects. [ABSTRACT FROM AUTHOR]

Summary: This study investigated the effects of l‐lysine (Lys) and l‐histidine (His) on the oxidative characteristics and gel properties of porcine myofibrillar proteins (MP). Results showed that Lys and His had a strong ferrous ion‐chelating ability and hydroxyl radical‐scavenging activity. Moreover, Lys and His inhibited the protein carbonyl formation and MP aggregation at 0.2 M and 0.6 M NaCl, respectively, in a dose‐dependent manner. Furthermore, 2 and 4 mg mL−1 Lys and His decreased the oxidation‐induced loss of the tertiary structure of MP accompanied by the lower surface hydrophobicity. The water‐holding capacity and gel strength of MP gels increased with increasing Lys and His concentrations due to more regular and lamellar structures with smaller and homogeneous pores at 0.6 M NaCl and more orderly crosslinking via fibrous filament at 0.2 M NaCl. In summary, Lys and His chelated the ferrous ions and scavenged hydroxyl radicals, decreased the oxidation‐induced physicochemical changes, thus preventing oxidative damage during the formation of a three‐dimensional gel network, which resulted in better gel quality. [ABSTRACT FROM AUTHOR]

ABSTRACT: Carnosine enrichment of slow-growing Korat chicken (KRC) meat helps differentiate KRC from mainstream chicken. We aimed to investigate the effects of β-alanine and L-histidine supplementation on the carnosine synthesis in and quality and secondary structure of proteins in slow-growing KRC meat. Four hundred 21-day-old female KRC were used, and a completely randomized design was applied. The chickens were divided into 4 experimental groups: basal diet (A), basal diet supplemented with 1.0% β-alanine (B), 0.5% L-histidine (C), and 1.0% β-alanine combined with 0.5% L-histidine (D). Each group consisted of 5 replicates (20 chickens per replicate). On d 70, 2 chickens per replicate were slaughtered, and the levels of carnosine, anserine, and thiobarbituric acid reactive substances were analyzed. Biochemical changes were monitored using synchrotron radiation-based Fourier transform infrared microspectroscopy; 5 chickens per replicate were slaughtered, and the meat quality was analyzed. Statistical analysis was performed using ANOVA and principal component analysis (PCA). Group D chickens exhibited the highest carnosine meat content, followed by those in groups B and C. However, amino acid supplementation did not affect anserine content and growth performance. Higher carnosine levels correlated with increasing pH45 min and decreasing drip loss, cooking loss, shear force, and lipid oxidation. PCA revealed that supplementation with only β-alanine or L-histidine was related to increased content of β-sheets, β-turns, and aliphatic bending groups and decreased content of α-helix groups. This study is the first to report such findings in slow-growing chicken. Our findings suggest that KRC can synthesize the highest carnosine levels after both β-alanine and L-histidine supplementation. Higher carnosine contents do not adversely affect meat quality, improve meat texture, and alter the secondary structures of proteins. The molecular mechanism underlying carnosine synthesis in chickens needs further study to better understand and reveal markers that facilitate the development of nutrient selection programs.