Search

We use first principles of population genetics to model the evolution of proteins under persistent positive selection (PPS). PPS may occur when organisms are subjected to persistent environmental change, during adaptive radiations, or in host–pathogen interactions. Our mutation–selection model indicates protein evolution under PPS is an irreversible Markov process, and thus proteins under PPS show a strongly asymmetrical distribution of selection coefficients among amino acid substitutions. Our model shows the criteria ω > 1 (where ω is the ratio of nonsynonymous over synonymous codon substitution rates) to detect positive selection is conservative and indeed arbitrary, because in real proteins many mutations are highly deleterious and are removed by selection even at positively selected sites. We use a penalized-likelihood implementation of the PPS model to successfully detect PPS in plant RuBisCO and influenza HA proteins. By directly estimating selection coefficients at protein sites, our inference procedure bypasses the need for using ω as a surrogate measure of selection and improves our ability to detect molecular adaptation in proteins. [ABSTRACT FROM AUTHOR]

Naturally occurring enzymes can be a source of unnatural reactivity that can be molded by directed evolution to generate efficient biocatalysts with valuable activities. Owing to the lack of exploitable stereocontrol elements in synthetic systems, steering the absolute and relative stereochemistry of free-radical processes is notoriously difficult in asymmetric catalysis. Inspired by the innate redox properties of first-row transition-metal cofactors, we repurposed cytochromes P450 to catalyze stereoselective atom-transfer radical cyclization. A set of metalloenzymes was engineered to impose substantial stereocontrol over the radical addition step and the halogen rebound step in these unnatural processes, allowing enantio- and diastereodivergent radical catalysis. This evolvable metalloenzyme platform represents a promising solution to tame fleeting radical intermediates for asymmetric catalysis. [ABSTRACT FROM AUTHOR]

Background and Objective: Cytochromes P450 (CYP) are the major enzymes involved in hepatic metabolism of drugs. Personalization of treatment in pediatrics is a major challenge, as it must not only take into account genetic, environmental, and physiological factors but also ontogeny. Published data in adults show that inflammation had an isoform-specific impact on CYP activities and we aimed to evaluate this impact in the pediatric population. Methods: Articles listed in PubMed through 7 January, 2021 that studied the impact of inflammation on CYP activities in pediatrics were included in this systematic review. Sources of inflammation, victim drugs (CYP involved), effect of drug–disease interactions, number and age of subjects, and study design were extracted. Results: Twenty-seven studies and case reports were included. The impact of inflammation on CYP activities appeared to be age dependent and isoform-specific, with some drug–disease interactions having significant pharmacokinetic and clinical impact. For example, midazolam clearance decreases by 70%, while immunosuppressant and theophylline concentrations increase three-fold and two-fold with intensive care unit admission and infection. Cytochrome P450 activity appears to return to baseline level when the disease is resolved. Conclusions: Studies that have assessed the impact of inflammation on CYP activity are lacking in pediatrics, yet it is a major factor to consider to improve drug efficacy or safety. The scarce current data show that the impact of inflammation is isoform and age dependent. An effort must be made to improve the understanding of the impact of inflammation on CYP activities in children to better individualize treatment. [ABSTRACT FROM AUTHOR]

ABSTRACT Conductive nanowires are thought to contribute to long-range electron transfer (LET) in Geobacter sulfurreducens anode biofilms. Three types of nanowires have been identified: pili, OmcS, and OmcZ. Previous studies highlighted their conductive function in anode biofilms, yet a structural function also has to be considered. We present here a comprehensive analysis of the function of nanowires in LET by inhibiting the expression of each nanowire. Meanwhile, flagella with poor conductivity were expressed to recover the structural function but not the conductive function of nanowires in the corresponding nanowire mutant strain. The results demonstrated that pili played a structural but not a conductive function in supporting biofilm formation. In contrast, the OmcS nanowire played a conductive but not a structural function in facilitating electron transfer in the biofilm. The OmcZ nanowire played both a structural and a conductive function to contribute to current generation. Expression of the poorly conductive flagellum was shown to enhance biofilm formation, subsequently increasing current generation. These data support a model in which multiheme cytochromes facilitate long-distance electron transfer in G. sulfurreducens biofilms. Our findings also suggest that the formation of a thicker biofilm, which contributed to a higher current generation by G. sulfurreducens, was confined by the biofilm formation deficiency, and this has applications in microbial electrochemical systems. IMPORTANCE The low power generation of microbial fuel cells limits their utility. Many factors can affect power generation, including inefficient electron transfer in the anode biofilm. Thus, understanding the mechanism(s) of electron transfer provides a pathway for increasing the power density of microbial fuel cells. Geobacter sulfurreducens was shown to form a thick biofilm on the anode. Cells far away from the anode reduce the anode through long-range electron transfer. Based on their conductive properties, three types of nanowires have been hypothesized to directly facilitate long-range electron transfer: pili, OmcS, and OmcZ nanowires. However, their structural contributions to electron transfer in anode biofilm have not been elucidated. Based on studies of mutants lacking one or more of these facilitators, our results support a cytochrome-mediated electron transfer process in Geobacter biofilms and highlight the structural contribution of nanowires in anode biofilm formation, which contributes to biofilm formation and current generation, thereby providing a strategy to increase current generation.

Cytochrome P450 isoenzymes have a major role in the metabolism of xenobiotics. They are mostly found in hepatocytes and oxidize majority of drugs, thus shifting them into their inactive form. Some of them can influence cytochromes’ activity while getting oxidized, simultaneously inducing or inhibiting them. This way, drug activity can be altered and their benefit in the management of the disease limited.

In recent years, the externalization of electrons as part of respiratory metabolic processes has been discovered in many different bacteria and some archaea. Microbial extracellular electron transfer (EET) plays an important role in many anoxic natural or engineered ecosystems. In this study, an anaerobic methane-converting microbial community was investigated with regard to its potential to perform EET. At this point, it is not well-known if or how EET confers a competitive advantage to certain species in methane-converting communities. EET was investigated in a two-chamber electrochemical system, sparged with methane and with an applied potential of +400 mV versus standard hydrogen electrode. A biofilm developed on the working electrode and stable low-density current was produced, confirming that EET indeed did occur. The appearance and presence of redox centers at −140 to −160 mV and at −230 mV in the biofilm was confirmed by cyclic voltammetry scans. Metagenomic analysis and fluorescence in situ hybridization of the biofilm showed that the anaerobic methanotroph ‘Candidatus Methanoperedens BLZ2’ was a significant member of the biofilm community, but its relative abundance did not increase compared to the inoculum. On the contrary, the relative abundance of other members of the microbial community significantly increased (up to 720-fold, 7.2% of mapped reads), placing these microorganisms among the dominant species in the bioanode community. This group included Zoogloea sp., Dechloromonas sp., two members of the Bacteroidetes phylum, and the spirochete Leptonema sp. Genes encoding proteins putatively involved in EET were identified in Zoogloea sp., Dechloromonas sp. and one member of the Bacteroidetes phylum. We suggest that instead of methane, alternative carbon sources such as acetate were the substrate for EET. Hence, EET in a methane-driven chemolithoautotrophic microbial community seems a complex process in which interactions within the microbial community are driving extracellular electron transfer to the electrode.

Oxidative stress greatly limits current harvesting from anode biofilms in bioelectrochemical systems yet insufficient knowledge of the antioxidant responses of electricigens prevents optimization. Using Geobacter sulfurreducens PCA as a model electricigen, we demonstrated enhanced oxygen tolerance and reduced electron losses as the biofilms grew in height on the anode. To investigate the molecular basis of biofilm tolerance, we developed a genetic screening and isolated 11 oxygen-tolerant (oxt) strains from a library of transposon-insertion mutants. The aggregative properties of the oxt mutants promoted biofilm formation and oxygen tolerance. Yet, unlike the wild type, none of the mutants diverted respiratory electrons to oxygen. Most of the oxt mutations inactivated pathways for the detoxification of reactive oxygen species that could have triggered compensatory chronic responses to oxidative stress and inhibit aerobic respiration. One of the mutants (oxt10) also had a growth advantage with Fe(III) oxides and during the colonization of the anode electrode. The enhanced antioxidant response in this mutant reduced the system's start-up and promoted current harvesting from bioanodes even in the presence of oxygen. These results highlight a hitherto unknown role of oxidative stress responses in the stability and performance of current-harvesting biofilms of G. sulfurreducens and identify biological and engineering approaches to grow electroactive biofilms with the resilience needed for practical applications.

Pesticides have increased crop yield but severely impacted ecosystems and non-target organisms. Flubendiamide, a new generation pesticide, targets insect larvae but also affects non-target organisms. This study examines the effects of lowest observed effect concentration of technical grade flubendiamide (0.5 µg/µL) flubendiamide on chick liver, focusing on cytochrome P450 (CYP) enzyme expression, oxidative stress, and liver damage. Chick embryos treated with flubendiamide showed significant alterations in CYP mRNA and protein levels, indicating increased toxicant accumulation. Elevated CYP3A4, CYP1A1, CYP1A2, and CYP2C19 levels were noted, suggesting enhanced biotransformation and detoxification processes. However, increased oxidative byproducts led to oxidative stress, as evidenced by decreased glutathione (GSH) levels and elevated superoxide dismutase (SOD) and catalase activities. DCFDA staining confirmed increased hydrogen peroxide (H 2 O 2 ) levels, indicating heightened reactive oxygen species (ROS). Liver function tests revealed significant increases in serum ALP, ALT, and AST levels, indicating acute liver damage. Histopathological analysis showed structural liver damage, including expanded sinusoidal spaces, impaired portal veins, and compromised hepatocyte architecture. These findings underscore flubendiamide's potential hepatotoxicity in non-target organisms, emphasizing the need for cautious pesticide use to minimize environmental impacts., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Heme consists of a tetrapyrrole ring ligating an iron ion and has important roles in biological systems. While well-known as the oxygen-binding molecule within hemoglobin of mammals, heme is also cofactor for several enzymes and a major iron source for bacteria within the host. The enterococci are a diverse group of Gram-positive bacteria that exist primarily within the gastrointestinal tract of animals. However, some species within this genus can transform into formidable opportunistic pathogens, largely owing to their extraordinary adaptability to hostile environments. Although enterococci cannot synthesize heme nor depend on heme to grow, several species within the genus encode proteins that utilize heme as a cofactor, which appears to increase their fitness and ability to thrive in challenging environments. This includes more efficient energy generation via aerobic respiration and protection from reactive oxygen species. Here, we review the significance of heme to enterococci, primarily the major human pathogen Enterococcus faecalis , use bioinformatics to assess the prevalence of hemoproteins throughout the genus, and highlight recent studies that underscore the central role of the heme- E. faecalis relationship in host-pathogen dynamics and interspecies bacterial interactions., Competing Interests: None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of FEMS.)

Background: Available in-vitro and animal studies indicate that inflammation impacts cytochromes P450 (CYP) activity via multiple and complex transcriptional and post-transcriptional mechanisms, depending on the specific CYP isoforms and the nature of inflammation mediators. It is essential to review the current published data on the impact of inflammation on CYP activities in adults to support drug individualization based on comorbidities and diseases in clinical practice. Methods: This systematic review was conducted in PubMed through 7th January 2021 looking for articles that investigated the consequences of inflammation on CYP activities in adults. Information on the source of inflammation, victim drugs (and CYPs involved), effect of disease-drug interaction, number of subjects, and study design were extracted. Results: The search strategy identified 218 studies and case reports that met our inclusion criteria. These articles were divided into fourteen different sources of inflammation (such as infection, autoimmune diseases, cancer, therapies with immunomodulator...). The impact of inflammation on CYP activities appeared to be isoform-specific and dependent on the nature and severity of the underlying disease causing the inflammation. Some of these drug-disease interactions had a significant influence on drug pharmacokinetic parameters and on clinical management. For example, clozapine levels doubled with signs of toxicity during infections and the concentration ratio between clopidogrel's active metabolite and clopidogrel is 48-fold lower in critically ill patients. Infection and CYP3A were the most cited perpetrator of inflammation and the most studied CYP, respectively. Moreover, some data suggest that resolution of inflammation results in a return to baseline CYP activities. Conclusion: Convincing evidence shows that inflammation is a major factor to be taken into account in drug development and in clinical practice to avoid any efficacy or safety issues because inflammation modulates CYP activities and thus drug pharmacokinetics. The impact is different depending on the CYP isoform and the inflammatory disease considered. Moreover, resolution of inflammation appears to result in a normalization of CYP activity. However, some results are still equivocal and further investigations are thus needed. [ABSTRACT FROM AUTHOR]

Microbiome is now considered as a significant metabolic organ with an immense potential to influence overall human health. A number of diseases that are associated with pharmacotherapy interventions was linked with altered gut microbiota. Moreover, it has been reported earlier that gut microbiome modulates the fate of more than 30 commonly used drugs and, vice versa, drugs have been shown to affect the composition of the gut microbiome. The molecular mechanisms of this mutual relationship, however, remain mostly elusive. Recent studies indicate an indirect effect of the gut microbiome through its metabolites on the expression of biotransformation enzymes in the liver. The aim of this study was to analyse the effect of gut microbiome on the fate of metronidazole in the mice through modulation of system of drug metabolizing enzymes, namely by alteration of the expression and activity of selected cytochromes P450 (CYPs). To assess the influence of gut microbiome, germ-free mice (GF) in comparison to control specific-pathogen-free (SPF) mice were used. First, it has been found that the absence of microbiota significantly affected plasma concentration of metronidazole, resulting in higher levels (by 30%) of the parent drug in murine plasma of GF mice. Further, the significant interaction between presence/absence of the gut microbiome and effect of metronidazole application, which together influence mRNA expression of CAR, PPARα, Cyp2b10 and Cyp2c38 was determined. Administration of metronidazole itself influenced significantly mRNA expression of Cyp1a2, Cyp2b10, Cyp2c38 and Cyp2d22. Finally, GF mice have shown lower level of enzyme activity of CYP2A and CYP3A than their SPF counterparts. The results hence have shown that, beside direct bacterial metabolism, different expression and enzyme activity of hepatic CYPs in the presence/absence of gut microbiota may be responsible for the altered metronidazole metabolism. [ABSTRACT FROM AUTHOR]

Natural microbes employing c‐type cytochromes (c‐Cyts) for extracellular electron transport (EET) were greatly valuable to develop redox‐based bioelectrochemical applications. However, low levels of c‐Cyt expression limited the phylogenetically diverse Gram‐positive species to be used in bioelectrochemical devices. This work reported the remarkable finding that a high level of c‐Cyts was expressed in the cells of the Gram‐positive strain Lysinibacillus varians GY32. c‐Cyts in Lysinibacillus varians GY32 cells were expressed at a level close to those in Shewanella oneidensis. These c‐Cyts were found to cluster in cytoplasmic membrane and periplasmic space, along the length of Lysinibacillus varians GY32 cell. With voltammetry and spectroelectrochemical titration, phenazine methosulfate‐mediated electron transfer between the c‐Cyts and an electrode was proved. These results expanded the accessible natural models of EET and suggested a new microbial platform for developing bioelectrochemical applications. [ABSTRACT FROM AUTHOR]

Members of class VII cytochromes P450 are catalytically self-sufficient enzymes containing a phthalate dioxygenase reductase-like domain fused to the P450 catalytic domain. Among these, CYP116B46 is the first enzyme for which the 3D structure of the whole polypeptide chain has been solved, shedding light on the interaction between its domains, which is crucial for catalysis. Most of these enzymes have been isolated from extremophiles or detoxifying bacteria that can carry out regio- and enantioselective oxidation of compounds of biotechnological interest. Protein engineering has generated mutants that can perform challenging organic reactions such as the anti-Markovnikov alkene oxidation. This potential, combined with the detailed 3D structure, forms the basis for further directed evolution studies aimed at widening their biotechnological exploitation. The self-sufficient nature of some bacterial cytochromes P450 makes them attractive biocatalysts as they do not require a redox partner protein for catalysis. The self-sufficient class VII is the first full length multidomain P450 for which the 3D structure has been solved. Many self-sufficient P450s are present in extremophiles in polluted sites, suggesting a high stability in extreme conditions, which is an advantage for biocatalysts and bioremediation purposes. Protein engineering has successfully targeted self-sufficient P450s: the reductase domain can supply electrons to other enzymes in chimeric fusion proteins, whereas the P450 domain can be designed for high activity and selectivity. Semi-rational and random mutagenesis have created variants with improved catalytic efficiency towards substrates of biotechnological interest that are converted in high value chemicals. [ABSTRACT FROM AUTHOR]

Acetogenic bacteria are a polyphyletic group of organisms that fix carbon dioxide under anaerobic, non-phototrophic conditions by reduction of two mol of CO2 to acetyl-CoA via the Wood–Ljungdahl pathway. This pathway also allows for lithotrophic growth with H2 as electron donor and this pathway is considered to be one of the oldest, if not the oldest metabolic pathway on Earth for CO2 reduction, since it is coupled to the synthesis of ATP. How ATP is synthesized has been an enigma for decades, but in the last decade two ferredoxin-dependent respiratory chains were discovered. Those respiratory chains comprise of a cytochrome-free, ferredoxin-dependent respiratory enzyme complex, which is either the Rnf or Ech complex. However, it was discovered already 50 years ago that some acetogens contain cytochromes and quinones, but their role had only a shadowy existence. Here, we review the literature on the characterization of cytochromes and quinones in acetogens and present a hypothesis that they may function in electron transport chains in addition to Rnf and Ech. [ABSTRACT FROM AUTHOR]

Progesterone receptor membrane component 1 (PGRMC1) is a heme-binding protein implicated in a wide range of cellular functions. We previously showed that PGRMC1 binds to cytochromes P450 in yeast and mammalian cells and supports their activity. Recently, the paralog PGRMC2 was shown to function as a heme chaperone. The extent of PGRMC1 function in cytochrome P450 biology and whether PGRMC1 is also a heme chaperone are unknown. Here, we examined the function of Pgrmc1 in mouse liver using a knockout model and found that Pgrmc1 binds and stabilizes a broad range of cytochromes P450 in a heme-independent manner. Proteomic and transcriptomic studies demonstrated that Pgrmc1 binds more than 13 cytochromes P450 and supports maintenance of cytochrome P450 protein levels posttranscriptionally. In vitro assays confirmed that Pgrmc1 KO livers exhibit reduced cytochrome P450 activity consistent with reduced enzyme levels. Mechanistic studies in cultured cells demonstrated that PGRMC1 stabilizes cytochromes P450 and that binding and stabilization do not require PGRMC1 binding to heme. Importantly, Pgrmc1-dependent stabilization of cytochromes P450 is physiologically relevant, as Pgrmc1 deletion protected mice from acetaminophen-induced liver injury. Finally, evaluation of Y113F mutant Pgrmc1, which lacks the axial heme iron-coordinating hydroxyl group, revealed that proper iron coordination is not required for heme binding, but is required for binding to ferrochelatase, the final enzyme in heme biosynthesis. PGRMC1 was recently identified as the causative mutation in X-linked isolated pediatric cataract formation. Together, these results demonstrate a heme-independent function for PGRMC1 in cytochrome P450 stability that may underlie clinical phenotypes. [ABSTRACT FROM AUTHOR]

Cytochromes P450 are versatile enzymes that function in endobiotic and xenobiotic metabolism and undergo meaningful structural changes that relate to their function. However, the way in which conformational changes inform the specific recognition of the substrate is often unknown. Here, we demonstrate the utility of fluorine (19F)-NMR spectroscopy to monitor structural changes in CYP121A1, an essential enzyme from Mycobacterium tuberculosis. CYP121A1 forms functional dimers that catalyze the phenol-coupling reaction of the dipeptide dicyclotyrosine. The thiol-reactive compound 3-bromo-1,1,1-trifluoroacetone was used to label an S171C mutation of the enzyme FG loop, which is located adjacent to the homodimer interface. Substrate titrations and inhibitor-bound 19F-NMR spectra indicate that ligand binding reduces conformational heterogeneity at the FG loop in both the dimer and in an engineered monomer of CYP121A1. However, only the dimer was found to promote a substrate-bound conformation that was preexisting in the substrate-free spectra, thus confirming a role for the dimer interface in dicyclotyrosine recognition. Moreover, 19F-NMR spectra in the presence of substrate analogs indicate the hydrogen-bonding feature of the dipeptide aromatic side chain as a dicyclotyrosine specificity criterion. This study demonstrates the utility of 19F-NMR as applied to a multimeric cytochrome P450, while also revealing mechanistic insights for an essential M. tuberculosis enzyme. [ABSTRACT FROM AUTHOR]

Coronavirus disease 2019 (COVID‐19), caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection, is a severe acute respiratory syndrome with an underlying inflammatory state. We have previously demonstrated that acute inflammation modulates cytochromes P450 (CYPs) activity in an isoform‐specific manner. We therefore hypothesized that COVID‐19 might also impact CYP activity, and thus aimed to evaluate the impact of acute inflammation in the context of SARS‐CoV‐2 infection on the six main human CYPs activity. This prospective observational study was conducted in 28 patients hospitalized at the Geneva University Hospitals (Switzerland) with a diagnosis of moderate to severe COVID‐19. They received the Geneva phenotyping cocktail orally during the first 72 hours of hospitalization and after 3 months. Capillary blood samples were collected 2 hours after cocktail administration to assess the metabolic ratios (MRs) of CYP1A2, 2B6, 2C9, 2C19, 2D6, and 3A. C‐reactive protein (CRP), interleukin 6 (IL‐6), and tumor necrosis factor‐α (TNF‐α) levels were also measured in blood. CYP1A2, CYP2C19, and CYP3A MRs decreased by 52.6% (P = 0.0001), 74.7% (P = 0.0006), and 22.8% (P = 0.045), respectively, in patients with COVID‐19. CYP2B6 and CYP2C9 MRs increased by 101.1% (P = 0.009) and 55.8% (P = 0.0006), respectively. CYP2D6 MR variation did not reach statistical significance (P = 0.072). As expected, COVID‐19 was a good acute inflammation model as mean serum levels of CRP, IL‐6, and TNF‐α were significantly (P < 0.001) higher during SARS‐CoV‐2 infection. CYP activity are modulated in an isoform‐specific manner by SARS‐CoV‐2 infection. The pharmacokinetics of CYP substrates, whether used to treat the disease or as the usual treatment of patients, could be therefore clinically impacted. [ABSTRACT FROM AUTHOR]

Background: Urushiols are pro-electrophilic haptens that cause severe contact dermatitis mediated by CD8+ effector T-cells and downregulated by CD4+ T-cells. However, the molecular mechanism by which urushiols stimulate innate immunity in the initial stages of this allergic reaction is poorly understood. Here we explore the sub-cellular mechanisms by which urushiols initiate the allergic response. Results: Electron microscopy observations of mouse ears exposed to litreol (3-n-pentadecyl-10-enyl-catechol]) showed keratinocytes containing swollen mitochondria with round electron-dense inclusion bodies in the matrix. Biochemical analyses of sub-mitochondrial fractions revealed an inhibitory effect of urushiols on electron flow through the mitochondrial respiratory chain, which requires both the aliphatic and catecholic moieties of these allergens. Moreover, urushiols extracted from poison ivy/oak (mixtures of 3-n-pentadecyl-8,11,13 enyl/3-n-heptadecyl-8,11 enyl catechol) exerted a higher inhibitory effect on mitochondrial respiration than did pentadecyl catechol or litreol, indicating that the higher number of unsaturations in the aliphatic chain, stronger the allergenicity of urushiols. Furthermore, the analysis of radioactive proteins isolated from mitochondria incubated with 3H-litreol, indicated that this urushiol was bound to cytochrome c1. According to the proximity of cytochromes c1 and b, functional evidence indicated the site of electron flow inhibition was within complex III, in between cytochromes bL (cyt b566) and bH (cyt b562). Conclusion: Our data provide functional and molecular evidence indicating that the interruption of the mitochondrial electron transport chain constitutes an important mechanism by which urushiols initiates the allergic response. Thus, mitochondria may constitute a source of cellular targets for generating neoantigens involved in the T-cell mediated allergy induced by urushiols. [ABSTRACT FROM AUTHOR]

Insight into mammalian respiratory complexes defines the role of allosteric protein interactions in their proton-motive activity. In cytochrome c oxidase (CxIV) conformational change of subunit I, caused by O 2 binding to heme a 3 2+-Cu B + and reduction, and stereochemical transitions coupled to oxidation/reduction of heme a and Cu A , combined with electrostatic effects, determine the proton pumping activity. In ubiquinone-cytochrome c oxidoreductase (CxIII) conformational movement of Fe–S protein between cytochromes b and c 1 is the key element of the proton-motive activity. In NADH-ubiquinone oxidoreductase (CxI) ubiquinone binding and reduction result in conformational changes of subunits in the quinone reaction structure which initiate proton pumping. • The role of allosteric protein interactions in mammalian respiratory complexes. • Conformational changes and electrostatic effects determine proton pumping in CxIV. • Role of conformational movement of Fe–S protein in proton-motive activity of CxIII. • Redox coupled subunits conformational changes initiate proton pumping in CxI. [ABSTRACT FROM AUTHOR]

Copyright of Praktické Lékárenství is the property of SOLEN sro and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Breeding young cattle is important, especially during the transition period from dairy feeding to concentrated dry feed. The paper presents the results of the use of biogenic metal nicotinates for weaning calves to improve metabolism in animals. The aim of research. To investigate the effect of biogenic metal nicotinates: Zn, Cu, Fe, Co, Mn on the biochemical parameters of blood in calves after weaning. Materials and methods. The study was carried out during 2021 in the conditions of LLC "Agrofirma Lan", Sumy region, Sumy district, Kindrativka, Ukraine for breeding young cattle. The calves of the experimental group were given compound feed and a premix of nicotinates of biogenic metals: Zn, Cu, Fe, Co, Mn, manufactured by PPronos Agro" (1 g per 1 kg of feed). In the control group, combined feed and a premix with metal sulfates were used for 30 days. Results. An increase in the level of total protein in the body of calves of the experimental groups was established by 16.12 % in comparison with the control (p≤0.05). Also, in experimental animals, the activity of the enzymes alanine aminotransferase and aspartate aminotransferase was higher than the physiological norm, which shows an insignificant effect of nicotinates of biogenic metals on internal organs and systems. In the experimental group of calves, the level of magnesium was probably higher by 52.38 % and potassium – by 14.94 % compared to the control group (p≤0.05). It was found that the animals of the experimental groups probably had more zinc by 34.96 %; copper – by 35.72 %; iron – by 92.29 %; manganese – by 41.13 %; selenium – by 3.22 % and cobalt – by 98.33 % compared to the control (p≤0.05). Conclusions. The positive effect of the use of biogenic metal nicotinates on the metabolism of calves at weaning has been proven. It was found that the level of total protein in the body of calves of the experimental groups was probably higher by 16.12 %, magnesium - by 52.38 %; potassium - by 14.94 %. When determining the content of inorganic substances, it was found that the animals of the experimental groups probably had more zinc by 34.96 %; copper – by 35.72 %; iron – by 92.29 %; manganese – by 41.13 %; selenium – by 3.22 % and cobalt – by 98.33 % compared to the control (p≤0.05). [ABSTRACT FROM AUTHOR]

[Figure: see text]. [ABSTRACT FROM AUTHOR]

Anthraquinones exhibit various pharmacological activities (e.g., antioxidant and laxative) and are commonly found in consumer products including foods, dietary supplements, drugs, and traditional medicines. Despite their widespread use, there are limited data available on their toxicokinetic properties. Cytochrome P450 enzymes (CYPs) in the liver play major roles in metabolizing exogenous chemicals (e.g., pharmaceuticals, food ingredients, and environmental pollutants) and endogenous biomolecules (e.g., steroid hormones and cholesterol). Inhibition of CYP activities may lead to serious interactions among these compounds. Here, in silico (quantitative structure‐activity relationship modeling) and in vitro (human recombinant enzymes and liver microsomes) methods were used to identify inhibitors of five major CYP isoforms (CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4) among 22 anthraquinones. First, in silico prediction and in vitro human recombinant enzyme assays were conducted for all compounds, and results showed that most of the anthraquinones were potent CYP1A2 inhibitors. Second, five selected anthraquinones (emodin, aloe‐emodin, rhein, purpurin, and rubiadin) were further evaluated in human liver microsomes. Finally, plasma concentrations of the five anthraquinones in animal and humans were identified in the literature and compared to their in vitro inhibition potency (IC50 values) towards CYP activities. Emodin, rhein, and aloe‐emodin inhibited activities of multiple CYPs in human liver microsomes and potential in vivo inhibition may occur due to their high plasma concentrations. These in silico and in vitro results enabled rapid identification of potential CYP inhibitors and prioritized future in‐depth studies. Anthraquinones exhibit various pharmacological activities and are found in various consumer products. Limited data are available on their inhibition towards liver cytochrome P450 enzymes, which metabolize numerous exogenous and endogenous compounds. Here, in silico and in vitro methods were used to identify inhibitors of five major CYP isoforms among 22 anthraquinones. Among the anthraquinones, emodin, rhein, and aloe‐emodin inhibited activities of multiple CYPs and potential in vivo inhibition may occur due to their high plasma concentrations. [ABSTRACT FROM AUTHOR]

Introduction: The molecular basis of in vivo metabolism of selected representatives of phenylethanoids in the presence of ethanol has not been fully elucidated. Objective: The aim was to estimate a salidroside (Sal) metabolism in the liver tissue in rats with induced alcohol tolerance by assessing changes in the transcription of genes encoding cytochromes: CYP1A2, 2D2, 3A1, 2C23. Methods: cDNA was synthesized from total RNA isolated from rat liver samples. mRNA level changes were evaluated using real-time PCR (qRT-PCR) technique. Results: Ethanol caused a significant induction of the CYP1A2 and CYP2C23 genes transcription, and a decrease in the CYP3A1 mRNA level, predominantly without statistical significance. A statistically significant increase of the CYP1A2 mRNA level was observed in the group receiving only Sal (4.5 mg/kg b.w.; p.o.) (p<0.01). Conclusions: There was no unequivocal effect of salidroside on the transcription of investigated cytochrome genes in the liver of rats with induced alcohol tolerance. [ABSTRACT FROM AUTHOR]

Magnetotactic bacteria have evolved complex subcellular machinery to construct linear chains of magnetite nanocrystals that allow the host cell to sense direction. Each mixed-valent iron nanoparticle is mineralized from soluble iron within a membrane-encapsulated vesicle termed the magnetosome, which serves as a specialized compartment that regulates the iron, redox, and pH environment of the growing mineral. To dissect the biological components that control this process, we have carried out a genetic and biochemical study of proteins proposed to function in iron mineralization. In this study, we show that the redox sites of c-type cytochromes of the Magnetospirillum magneticum AMB-1 magnetosome island, MamP and MamT, are essential to their physiological function and that ablation of one or both heme motifs leads to loss of function, suggesting that their ability to carry out redox chemistry in vivo is important. We also develop a method to heterologously express fully heme-loaded MamP from AMB-1 for in vitro biochemical studies, which show that its Fe(III)-Fe(II) redox couple is set at an unusual potential (-89 ± 11 mV) compared with other related cytochromes involved in iron reduction or oxidation. Despite its low reduction potential, it remains competent to oxidize Fe(II) to Fe(III) and mineralize iron to produce mixed-valent iron oxides. Finally, in vitro mineralization experiments suggest that Mms mineral-templating peptides from AMB-1 can modulate the iron redox chemistry of MamP.