Enzyme Complex Research Articles

Insights into bacterial interactions: Comparing fluorine-containing 1,2,4-triazoles to antibiotics using molecular docking and molecular dynamics approaches

Understanding the interactions between drugs and enzymes is crucial for designing effective therapeutics. This study employed a combination of molecular docking and molecular dynamics (MD) simulations to evaluate the binding affinity, stability, and dynamic behavior of two new compounds (compound 1 and compound 2) compared to vancomycin and meropenem against Staphylococcus aureus and Serratia marcescens bacterial enzymes. Molecular docking studies provided insights into the binding interactions and affinities of these compounds, revealing that both compound 1 and compound 2 exhibit promising binding profiles. In particular, compound 1 demonstrated lower binding energies with key enzymes from Staphylococcus aureus compared to vancomycin, suggesting enhanced potential. MD simulations further elucidated the dynamic stability of these complexes. Results indicated that compound 1 maintains consistent binding modes with low RMSD and RMSF values, implying stable interactions. In contrast, vancomycin exhibited high RMSD and RMSF values in some enzyme complexes, reflecting potential instability. Compound 2 showed competitive stability and binding behavior compared to meropenem, with comparable RMSD and RMSF values across various enzyme targets. These findings highlight the potential of compound 1 and compound 2 as viable candidates for further development, offering insights into their stability and efficacy as new therapeutic agents.

Enhanced emulsion capacity and gel properties of bighead carp myofibrillar protein through interaction with fresh maize bran arabinoxylan extracted by complex enzymes

SummaryBighead carp has the largest production amount among freshwater fish in China, but its physicochemical properties change rapidly with the denaturation of their myofibril protein (MP). The protein–polysaccharide complexes have shown interesting physicochemical properties as stabilisers and emulsifiers. In this study, arabinoxylans (AXs) were prepared and mixed with bighead carp MP to form a composite gel. The effect of AXs on the thermal stability, emulsification and emulsion stability of the composite gel was investigated. The results showed that fraction precipitated by 60% ethanol (F60) and by 90% (F90) improved the denaturation temperature of bighead carp MP from 65.99 °C to 67.39 °C and 68.22 °C, respectively. The emulsifying capacity of F60 (0.54 m2 g−1) was similar to that of sucrose (0.52 m2 g−1). The effect of F90 on the emulsion stability of bighead carp MP was better than that of F60. The elasticity of bighead carp MP was improved by F60 and F90. The hydroxyl group interactions, hydrophobic interactions and electrostatic forces exist between the macromolecules. AXs of fresh maize bran could prevent protein denaturation and improve the emulsion capacity and gel properties of bighead carp MP.

Development of a method for inactivating lipoxygenases in linseed using chemical reagents

The object of the study is the oxidative stability of the lipid component of linseed treated with a citric acid and sodium chloride solution. The rational composition of chemical reagents for inactivating linseed lipoxygenases was determined in the work. The obtained results make it possible to develop an effective linseed treatment method for increasing stability to oxidative spoilage. The proposed composition of the linseed treatment solution (citric acid – 1.0...1.3 %; sodium chloride – 0.6...0.8 %) significantly reduces the peroxide and anisidine numbers of the lipid component. This helps reduce oxidative spoilage during accelerated oxidation and storage under normal conditions. Rational treatment conditions were determined based on the approximate dependency of these indicators on the concentrations of chemical reagents. The data obtained in the work are explained by chemical interactions between the solution components and the enzyme complex of linseed, leading to enzyme denaturation and, accordingly, increased oxidative stability of the lipid component. A feature of the obtained results is the competitiveness of treated linseed, characterized by increased nutritional value due to improved technological properties. The results of the study allow minimizing the loss of nutritional value and increasing the shelf life of linseed products. The results are important for developing new oilseed processing technologies. This makes it possible not only to increase the stability of products against oxidative spoilage, but also to preserve their high nutritional value. Further research in this area will contribute to improving oilseed processing technologies, in particular linseed, which is an important contribution to the development of the food industry

Computational design of serine hydrolases.

Enzymes that proceed through multistep reaction mechanisms often utilize complex, polar active sites positioned with sub-angstrom precision to mediate distinct chemical steps, which makes their de novo construction extremely challenging. We sought to overcome this challenge using the classic catalytic triad and oxyanion hole of serine hydrolases as a model system. We used RFdiffusion1 to generate proteins housing catalytic sites of increasing complexity and varying geometry, and a newly developed ensemble generation method called ChemNet to assess active site geometry and preorganization at each step of the reaction. Experimental characterization revealed novel serine hydrolases that catalyze ester hydrolysis with catalytic efficiencies (k cat /K m ) up to 3.8 x 103 M-1 s-1, closely match the design models (Cα RMSDs < 1 Å), and have folds distinct from natural serine hydrolases. In silico selection of designs based on active site preorganization across the reaction coordinate considerably increased success rates, enabling identification of new catalysts in screens of as few as 20 designs. Our de novo buildup approach provides insight into the geometric determinants of catalysis that complements what can be obtained from structural and mutational studies of native enzymes (in which catalytic group geometry and active site makeup cannot be so systematically varied), and provides a roadmap for the design of industrially relevant serine hydrolases and, more generally, for designing complex enzymes that catalyze multi-step transformations.

Toward the Use of Methyl-Coenzyme M Reductase for Methane Bioconversion Applications.

ConspectusAs the main component of natural gas and renewable biogas, methane is an abundant, affordable fuel. Thus, there is interest in converting these methane reserves into liquid fuels and commodity chemicals, which would contribute toward mitigating climate change, as well as provide potentially sustainable routes to chemical production. Unfortunately, specific activation of methane for conversion into other molecules is a difficult process due to the unreactive nature of methane C-H bonds. The use of methane activating enzymes, such as methyl-coenzyme M reductase (MCR), may offer a solution. MCR catalyzes the methane-forming step of methanogenesis in methanogenic archaea (methanogens), as well as the initial methane oxidation step during the anaerobic oxidation of methane (AOM) in anaerobic methanotrophic archaea (ANME). In this Account, we highlight our contributions toward understanding MCR catalysis and structure, focusing on features that may tune the catalytic activity. Additionally, we discuss some key considerations for biomanufacturing approaches to MCR-based production of useful compounds.MCR is a complex enzyme consisting of a dimer of heterotrimers with several post-translational modifications, as well as the nickel-hydrocorphin prosthetic group, known as coenzyme F430. Since MCR is difficult to study in vitro, little information is available regarding which MCRs have ideal catalytic properties. To investigate the role of the MCR active site electronic environment in promoting methane synthesis, we performed electric field calculations based on molecular dynamics simulations with a MCR from Methanosarcina acetivorans and an ANME-1 MCR. Interestingly, the ANME-1 MCR active site better optimizes the electric field with methane formation substrates, indicating that it may have enhanced catalytic efficiency. Our lab has also worked toward understanding the structures and functions of modified F430 coenzymes, some of which we have discovered in methanogens. We found that methanogens produce modified F430s under specific growth conditions, and we hypothesize that these modifications serve to fine-tune the activity of MCR.Due to the complexity of MCR, a methanogen host is likely the best near-term option for biomanufacturing platforms using methane as a C1 feedstock. M. acetivorans has well-established genetic tools and has already been used in pilot methane oxidation studies. To make methane oxidation energetically favorable, extracellular electron acceptors are employed. This electron transfer can be facilitated by carbon-based materials. Interestingly, our analyses of AOM enrichment cultures and pure methanogen cultures revealed the biogenic production of an amorphous carbon material with similar characteristics to activated carbon, thus highlighting the potential use of such materials as conductive elements to enhance extracellular electron transfer.In summary, the possibilities for sustainable MCR-based methane conversions are exciting, but there are still some challenges to tackle toward understanding and utilizing this complex enzyme in efficient methane oxidation biomanufacturing processes. Additionally, further work is necessary to optimize bioengineered MCR-containing host organisms to produce large quantities of desired chemicals.

Short-chain fructooligosaccharides synthesis using a commercial enzyme complex from Aspergillus sp. and anti-cancer activity on HCT116 and HT-29 cell lines

Over the last years, short-chain fructooligosaccharides (FOS) have gained significant attention as valuable food and dietary supplement components. Apart from implications such as dietary fibres, sweeteners, and humectants, FOS are hailed for their prebiotic properties. Moreover, much research is dedicated to their role as anti-cancer agents. Despite the ongoing interest, both technical aspects, challenges of FOS production, and their anti-cancer role necessitate more in-depth investigations to understand their healthcare role better. This study aimed to optimise critical FOS synthesis parameters using a commercial enzyme, Viscozyme® L, to obtain a preparation with a high FOS content. A central composite design and response surface methodology evaluated the effect of pH, temperature, synthesis time, substrate, and enzyme load on multiple responses, chosen as independent variables, were utilised to define optimal conditions. Under the optimal conditions (temperature 50 °C, pH 5.5, sucrose concentration 352 g/L, enzyme concentration 2.5% v/v, and 5.5 h of reaction), a preparation with a total FOS content of 58.8% was obtained. The FOS preparation showed minimal in vitro antioxidant capacity in the ORAC, CUPRAC, and ABTS*+assays. In addition, the cytotoxicity of FOS against tested cell lines was evaluated. FOS did not reduce HT-29 cell viability even at the concentration of 2.5 mg/mL, whereas FOS inhibited the proliferation of HCT116 cells by 50% at 2.35 mg/mL. Finally, the sensitisation effect of FOS on HCT116 cell treatment with doxorubicin has been revealed.

Structure and function of a 1-MDa electron-confurcating/bifurcating, dearomatising enzyme complex from obligate anaerobic bacteria

Structure and function of a 1-MDa electron-confurcating/bifurcating, dearomatising enzyme complex from obligate anaerobic bacteria

Molecular mechanism of thiocyanate dehydrogenase at atomic resolution

Some sulfur-oxidizing bacteria playing an important role in global geochemical cycles utilize thiocyanate as the sole source of energy and nitrogen. In these bacteria the process of thiocyanate into cyanate conversion is mediated by thiocyanate dehydrogenases — a recently discovered family of copper-containing enzymes with the three‑copper active site unique among the other copper proteins. To get a deeper insight into the structure and molecular mechanism of action of thiocyanate dehydrogenases we isolated, purified, and comprehensively characterized an enzyme from the bacterium Pelomicrobium methylotrophicum. High-resolution crystal structures of the thiocyanate dehydrogenase in the free state and in the complexes with the transition state analog, thiourea, and the closest substrate analog, selenocyanate, unveiled the fine details of molecular events occurring at the enzyme active site. During the reaction thiocyanate dehydrogenase undergoes profound conformational change that affects the position of the constituent copper ions and results in the activation of the attacking water molecule. The structure of the enzyme complex with the selenium atom bridged in-between two copper ions was obtained representing an important transient intermediate. Structures of the complexes with inhibitors supplemented with quantum chemical calculations clarify the role of copper ions and refine molecular mechanism of catalysis by thiocyanate dehydrogenase.

Multivariate analysis of structural and functional properties of soluble dietary fiber from corn bran using different modification methods

This study comprehensively investigated the effects of high-temperature cooking (HT), complex enzyme hydrolysis (CE), and high-temperature cooking combined enzymatic hydrolysis (HE) on the chemical composition, microstructure, and functional attributes of soluble dietary fiber (SDF) extracted from corn bran. The results demonstrated that HE-SDF yielded the highest output at 13.80 ± 0.20 g/100 g, with enhancements in thermal stability, viscosity, hydration properties, adsorption capacity, and antioxidant activity. Cluster analysis revealed three distinct categories of SDF's physicochemical properties. Principal component analysis (PCA) confirmed the superior functional properties of HE-SDF. Correlation analysis showed positive relationships between the monosaccharide composition, purity, and viscosity of SDF and most of its functional attributes, whereas particle size and zeta potential were inversely correlated. Furthermore, a highly significant positive correlation was observed between crystallinity and thermal properties. These findings suggest that the HE method constitutes a viable strategy for enhancing the quality of SDF sourced from corn bran.

Review : Maple Syrup Urine Disease : A Rare Inherted Disorder of Amino Acid Metabolism

Maple syrup urine disease is a rare and serious condition in which the amino acid metabolism is impaired. Mostly it is inherited in an autosomal recessive pattern in neonates from birth itself. Normally our body breakdowns proteins into amino acid and further amino acids are broken down and removed from our body. but in this disease body loses it’s ability to breakdown amino acids causing harmful buildup of substances in blood and urine. It can cause life threatening cerebral oedema and dysmyelination in affected individuals. It is generally caused by the deficiency of enzyme complex (Branched chain alpha keto acid dehydrogenase(BCKDHA)) .this particular enzyme complex is necessary to breakdown the three branched chain amino acids(BCCA) leucine, isoleucine and valine. this results in the accumulation of all three amino acids in body producing toxic effects. The common symptoms of this disease in neonates includes: anorexia, sweet smell in the urine, irritability, weight loss. In classic MSUD neonates are even born asymptomatic but delay in treatment may lead to worsening of symptoms in their later stage of life. The toxic effects are due to accumulation of branched chain ketoacids(BCKAs)causing severe ketoacidosis and harmful effects of leucine on brain. however, this disease can be managed by a restricted diet containing low protein so that the three BCCAs are controlled to some extent and through continuous metabolic monitoring. Newborn screening for MSUD is also ver common now a days for diagnosis of MSUD in newborns.

Directional co-immobilization of artificial multimeric-enzyme complexes as a robust biocatalyst for biosynthesis curcumin glucosides and regeneration of UDP-glucose

Site-directed protein immobilization allows the homogeneous orientation of proteins while maintaining high activity, which is advantageous for various applications. In this study, the use of SpyCatcher/SpyTag technology and magnetic nickel ferrite (NiFe2O4 NPs) nanoparticles were used to prepare a site-directed immobilization of BsUGT2m from Bacillus subtilis and AtSUSm from Arabidopsis thaliana for enhancing curcumin glucoside production with UDP-glucose regeneration from sucrose and UDP. The immobilization of self-assembled multienzyme complex (MESAs) enzymes were characterized for immobilization parameters and stability, including thermal, pH, storage stability, and reusability. The immobilized MESAs exhibited a 2.5-fold reduction in UDP consumption, enhancing catalytic efficiency. Moreover, the immobilized MESAs demonstrated high storage and temperature stability over 21 days at 4 °C and 25 °C, outperforming their free counterparts. Reusability assays showed that the immobilized MESAs retained 78.7 % activity after 10 cycles. Utilizing fed-batch technology, the cumulative titer of curcumin 4’-O-β-D-glucoside reached 6.51 mM (3.57 g/L) and 9.45 mM (5.18 g/L) for free AtSUSm/BsUGT2m and immobilized MESAs, respectively, over 12 h. This study demonstrates the efficiency of magnetic nickel ferrite nanoparticles in co-immobilizing enzymes, enhancing biocatalysts' catalytic efficiency, reusability, and stability.

A structural perspective on the temperature-dependent activity of enzymes.

Enzymes are biomolecular catalysts whose activity varies with temperature. Unlike for small-molecule catalysts, the structural ensembles of enzymes can vary substantially with temperature, and it is in general unclear how this modulates the temperature dependence of activity. Here multi-temperature X-ray crystallography was used to record structural changes from -20°C to 40°C for a mesophilic enzyme in complex with inhibitors mimicking substrate-, intermediate-, and product-bound states, representative of major complexes underlying the kinetic constant . Both inhibitors, substrates and catalytically relevant loop motifs increasingly populate catalytically competent conformations as temperature increases. These changes occur even in temperature ranges where kinetic measurements show roughly linear Arrhenius/Eyring behavior where parameters characterizing the system are assumed to be temperature independent. Simple analysis shows that linear Arrhenius/Eyring behavior can still be observed when the underlying activation energy / enthalpy values vary with temperature, e.g., due to structural changes, and that the underlying thermodynamic parameters can be far from values derived from Arrhenius/Eyring model fits. Our results indicate a critical role for temperature-dependent atomic-resolution structural data in interpreting temperature-dependent kinetic data from enzymatic systems.

Exploring the differences in sauce‐flavour Daqu from different regions and its contribution to Baijiu brewing based on microbial communities and flavours

SummaryDaqu is an essential saccharification and fermentation agent in Baijiu brewing, and its characteristics affect the yield, quality, and flavour of Baijiu. The fundamental reason is that Daqu can provide rich microbial resources, complex enzyme systems, and raw materials for the Baijiu brewing process. In this study, three sauce‐flavour Daqu from two production areas, Beijing and Guizhou, were selected to focus on discussing and analysing the main contributions of sauce‐flavour Daqu itself to Baijiu brewing without interference from the external environment. The differences in the flavour composition and microbial communities of three Daqu were analysed. Microbial biomarkers were analysed by Lefse multilevel discriminant analysis for three Daqu. We found that different regions have their own biomarkers. Citrobacter, Rhodococcus, and Pseudomonas, were biomarkers of HD Daqu. Oceanobacillus, Aspergillus and Pichia were biomarkers of MT Daqu. Bacillus, Pediococcus and Fusarium were biomarkers of WM Daqu. A solid‐state simulation fermentation experiment was carried out to analyse changes in the flavour composition and microbial communities of fermented grains after 35 days of fermentation. The results showed that the microbial communities and the flavour composition in the Daqu and fermented samples differed significantly. The dominant microorganism genus evolved from Citrobacter, Rhodococcus, and Thermomyces to Lactobacillus, Pediococcus, and Pichia HD sample. The dominant microorganism genus in WM sample changed from Virgibacillus, Oceanobacillus, and Thermomyces to Lactobacillus, Pediococcus, and Pichia. Whereas in MT sample, the dominant microorganism genus evolved from Virgibacillus, Kroppenstedtia, and Thermomyces to Lactobacillus, Pediococcus, and Pichia. Additionally, the main flavour composition also changed after fermentation, which in the late fermentation period were phenylethyl alcohol, ethyl palmitate, tetramethylpyrazine, and 3‐methylbutanoic acid. These findings can provide support to explain the importance and contribution of sauce‐flavour Daqu in Baijiu brewing scientifically.

Cryo-EM Structure of the Mnx Protein Complex Reveals a Tunnel Framework for the Mechanism of Manganese Biomineralization.

The global manganese cycle relies on microbes to oxidize soluble Mn(II) to insoluble Mn(IV) oxides. Some microbes require peroxide or superoxide as oxidants, but others can use O2 directly, via multicopper oxidase (MCO) enzymes. One of these, MnxG from Bacillus sp. strain PL-12, was isolated in tight association with small accessory proteins, MnxE and MnxF. The protein complex, called Mnx, has eluded crystallization efforts, but we now report the 3D structure of a point mutant using cryo-EM single particle analysis, cross-linking mass spectrometry, and AlphaFold Multimer prediction. The β-sheet-rich complex features MnxG enzyme, capped by a heterohexameric ring of alternating MnxE and MnxF subunits, and a tunnel that runs through MnxG and its MnxE3F3 cap. The tunnel dimensions and charges can accommodate the mechanistically inferred binuclear manganese intermediates. Comparison with the Fe(II)-oxidizing MCO, ceruloplasmin, identifies likely coordinating groups for the Mn(II) substrate, at the entrance to the tunnel. Thus, the 3D structure provides a rationale for the established manganese oxidase mechanism, and a platform for further experiments to elucidate mechanistic details of manganese biomineralization.

Computer-aided design, synthesis, and biological evaluation of 4-chloro-N-(2-oxo-3-(2-pyridin-4-yl)hydrazineylidene)indolin-5yl)benzamide and 1-(4-bromobenzyl)-5-indoline-2,3-dione against SARS-CoV-2 spike/ACE2

The emergence of the severe acute respiratory syndrome 2 (SARS-CoV-2) as a global threat has driven the urgent need for the identification of bioactive molecules capable of controlling or completely eradicating this virus. Our group has been investigating isatin hybrids that block the binding of the human angiotensin-converting enzyme 2 (ACE2) and the viral spike protein. This work describes the synthesis and biological evaluation of two derivatives of isatin (indol-2,3-dione) based on a computational approach. Isatin, a secondary metabolite of tryptophan, has been used as the core structure and is a versatile and favorable precursor and as a privileged scaffold against this enzyme complex. The new compound scaffolds AVS-01 and AVS-02 were designed by modifications at the C-3 and N-1 positions, respectively, according to the various reagents available in our lab. Molecular docking of the designed compounds was used to explore their interactions with the target protein complex. The two designed compound scaffolds shown in this article showed quite distinct docking glide scores (GScore = −3.657 and −4.534 for AVS-01 and AVS-02, respectively). Several analogs were synthesized and tested in the quest to find a plausible scaffold for further synthesis. While compound AVS-02 showed inhibition of spike/ACE2 binding with an IC50 value of 8.8 µM, the reference compound hopeaphenol inhibited the interaction with an IC50 of 0.3 µM. Compound AVS-01 rather showed no inhibition of the SARS-CoV-2 spike/host ACE2 interaction with an IC50 > 32 µM. An estimation of their binding free energy (ΔGbind), and free energy of solvation (ΔGsolv) MM-GBSA calculations was carried out to re-evaluate the affinity to the target protein to gain further insights into the observed activity and non-activity. MM-GBSA calculation showed that ΔGbind = −35.91 kcal/mol and-25.32 kcal/mol for AVS-01 and AVS-02, respectively, and ΔGsolv = 25.56 kcal/mol and 16.92 kcal/mol for AVS-01 and AVS-02, respectively. This leads to the conclusion that the N-1 position of the indole-2,3-dione moiety favors the blockage of SARS-CoV-2 spike/ACE2 interactions compared to the C-3 position. Analysis of GScores, per-residue interaction energies, and free energies of binding and solvation showed that van der Waals interactions should favor the binding towards the spike/ACE2 complex.

Enzymatically Mediated In Situ Generation of Z-Scheme Bi2S3/Bi2MoO6 Heterojunction-Based Organic Photoelectrochemical Transistor for METTL3/METTL14 Detection.

The OPECT biosensing platform, which connects optoelectronics and biological systems, offers significant amplification and more possibilities for research in biological applications. In this work, a homogeneous organic photoelectrochemical transistor (OPECT) biosensor based on a Bi2S3/Bi2MoO6 heterojunction was constructed to detect METTL3/METTL14 protein activity. The METTL3/METTL14 complex enzyme was used to catalyze adenine (A) on an RNA strand to m6A, protecting m6A-RNA from being cleaved by an E. coli toxin (MazF). Alkaline phosphatase (ALP) catalyzed the conversion of Na3SPO3 to H2S through an enzymatic reaction. Due to the adoption of the strategy of no fixation on the electrode, the generated H2S was easy to diffuse to the surface of the ITO electrode. The Bi2S3/Bi2MoO6 heterojunction was formed in situ through a chemical replacement reaction with Bi2MoO6, improving photoelectric conversion efficiency and realizing signal amplification. Based on this "signal on" mode, METTL3/METTL14 exhibited a wide linear range (0.00001-25 ng/μL) between protein concentration and photocurrent intensity with a limit of detection (LOD) of 7.8 fg/μL under optimal experimental conditions. The applicability of the developed method was evaluated by investigating the effect of four plasticizers on the activity of the METTL3/METTL14 protein, and the molecular modeling technique was employed to investigate the interaction between plasticizers and the protein.

Delayed treatment with hydro-ethanolic extract of Khaya grandifoliola protects mice from acetaminophen-hepatotoxicity through inhibition of c-Jun N-terminal kinase phosphorylation and mitochondrial dysfunction

The use of N-acetylcysteine against acetaminophen(APAP)-induced hepatotoxicity, a leading cause of liver injury, has several drawbacks, including short therapeutic windows. Khaya grandifoliola (Meliaceae) has been traditionally used to manage liver-related diseases, and many reports have confirmed its hepatoprotective properties. However, its therapeutic potential as an antidote against APAP-induced hepatotoxicity has yet to be proven in a clinically relevant model. This study aimed to verify the efficacy of delayed treatment with the hydroethanolic extract of K. grandifoliola (KgE) in suppressing the early injury phase of APAP pathophysiology. KgE was analyzed using HPLC/UV. Acute oral toxicity tests were conducted in mice to determine the therapeutic dose of KgE. Mice were treated with 300 ​mg/kg APAP; 1h and 12h later, they were treated with either predetermined doses of KgE or 20 ​mg/kg c-Jun N-Terminal Kinase (JNK) inhibitor SP600125, which served as a reference antidote. At 6h and 24h after APAP treatment, the parameters of liver damage and mitochondrial dysfunction, phosphorylation of JNK, and mitochondrial translocation were assessed. KgE at a dose of 5000 ​mg/kg was safe for mice. Accordingly, 100, 200, and 400 ​mg/kg were selected as curative treatments. Delayed administration of KgE reversed the histopathological changes in the liver, inhibited serum levels of alanine aminotransferase, reduced the liver content of nitric oxide and malondialdehyde, and restored hepatic glutathione pools and superoxide dismutase and catalase activities in APAP-intoxicated mice. Moreover, KgE prevented APAP-induced JNK phosphorylation and p-JNK mitochondrial translocation and rescued the activities of mitochondrial enzyme complexes II and V. HPLC/UV analysis revealed the presence of gallic acid, Quercetin and Silibinin, with retention times of 3.77, 11.63 and 11.95 ​min as the major active ingredients present in KgE. Our findings demonstrate that post-treatment with KgE protects the mouse liver from APAP-hepatotoxicity through the inhibition of JNK activation and mitochondrial dysfunction.

Methanobactins: Structures, Biosynthesis, and Microbial Diversity.

Methanobactins (Mbns) are ribosomally synthesized and posttranslationally modified peptide natural products released by methanotrophic bacteria under conditions of copper scarcity. Mbns bind Cu(I) with high affinity via nitrogen-containing heterocycles and thioamide groups installed on a precursor peptide, MbnA, by a core biosynthetic enzyme complex, MbnBC. Additional stabilizing modifications are enacted by other, less universal biosynthetic enzymes. Copper-loaded Mbn is imported into the cell by TonB-dependent transporters called MbnTs, and copper is mobilized by an unknown mechanism. The machinery to biosynthesize and transport Mbn is encoded in operons that are also found in the genomes of nonmethanotrophic bacteria. In this review, we provide an update on the state of the Mbn field, highlighting recent discoveries regarding Mbn structure, biosynthesis, and handling as well as the emerging roles of Mbns in the environment and their potential use as therapeutics.

Inhibition of histone methyltransferase promotes cognition and mitochondrial function in vascular dementia model

Vascular dementia (VD) is one of the most common forms of dementia worldwide, characterized by problems with reasoning, planning, judgment, and memory. This study investigated the effect of a histone methyltransferase inhibitor on cognition and mitochondrial function in a rat model of VD, as well as its impact on H2O2-induced neurotoxicity in hippocampal neuronal cultures. In the in vivo experiments, VD was induced by bilateral occlusion of the common carotid artery (CCA) for one month. The histone methyltransferase inhibitor, BIX01294, was administered intracerebroventricularly for one month (22.5 µg.kg−1 three times/week). On day 30, behavioral tests, including the novel object recognition test and elevated plus maze test, were conducted. Mitochondrial enzyme activities, including aconitase, α-ketoglutarate dehydrogenase (α-KG), complex I, and complex IV, were evaluated in the hippocampus of rats following CCA ligation. In the in vitro experiments, the effect of BIX01294 (50–600 μM) on H2O2 (400 µM)-induced cytotoxicity in hippocampal neuronal cells was assessed using the MTT assay. Flow cytometry was performed to evaluate apoptosis. Our findings revealed that BIX01294 effectively improved memory function, Krebs cycle enzyme activity, and mitochondrial function in the rat model of VD. Moreover, in vitro results showed that BIX01294 at a concentration of 100 µM significantly reversed the cytotoxicity and apoptosis induced by H2O2 in neuronal cells. These findings suggest that BIX01294 may have the potential to improve VD complications by reducing oxidative stress and inhibiting histone methylation.

Evaluation of a carbohydrase (xylanase and glucanase) enzyme complex in diets for Florida pompano Trachinotus carolinus

AbstractFlorida pompano, Trachinotus carolinus, can be fed soy‐based, low‐animal protein diets. However, anti‐nutritional factors and carbohydrates limit digestibility. Dietary carbohydrase enzymes have been used to improve carbohydrate digestibility in several species and may be beneficial for Florida pompano. The present study was designed to evaluate the effects of using a carbohydrase enzyme complex (Natugrain® TS L, BASF Corporation, Ludwigshafen, Germany) composed of endo‐1,4‐ß‐xylanase and endo‐1,4‐ß‐glucanase (Xyl + Glu) on growth performance, feed utilization, and digestibility in diets fed to juvenile Florida pompano. A growth trial was conducted with iso‐nitrogenous (40%) and iso‐lipidic (8%) test diets containing 0, 0.015, 0.030, and 0.045% of Xyl + Glu. The trial was conducted in a recirculating system with 12, 1000‐L tanks. Twenty fish (mean weight: 23.34 g ± 1.49 g) were stocked into each tank in a randomized design. Growth results indicated that there were no significant differences (p &gt; 0.05) in growth and feed conversion; however, thermal growth coefficient displayed significant differences (p = 0.0499) between the 0.015 and 0.030% inclusion. All enzymatic treatments displayed significant differences (p = 0.029) in apparent digestibility of crude protein compared with the basal diet. Results indicate that Xyl + Glu enzyme complex can impact protein digestibility but did not significantly affect growth performance.