Metabolic Enzymes Research Articles

Crystal structure of glycerol kinase from Trypanosoma cruzi, a potential molecular target in Chagas disease.

Chagas disease is a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi. It bears a significant global health burden with limited treatment options, thus calling for the development of new and effective drugs. Certain trypanosomal metabolic enzymes have been suggested to be druggable and valid for subsequent inhibition. In this study, the crystal structure of glycerol kinase from T. cruzi, a key enzyme in glycerol metabolism in this parasite, is presented. Structural analysis allowed a detailed description of the glycerol binding pocket, while comparative assessment pinpointed a potential regulatory site which may serve as a target for selective inhibition. These findings advance the understanding of glycerol metabolism in eukaryotes and provide a solid basis for the future treatment of Chagas disease.

MetaPredictor: in silico prediction of drug metabolites based on deep language models with prompt engineering.

Metabolic processes can transform a drug into metabolites with different properties that may affect its efficacy and safety. Therefore, investigation of the metabolic fate of a drug candidate is of great significance for drug discovery. Computational methods have been developed to predict drug metabolites, but most of them suffer from two main obstacles: the lack of model generalization due to restrictions on metabolic transformation rules or specific enzyme families, and high rate of false-positive predictions. Here, we presented MetaPredictor, a rule-free, end-to-end and prompt-based method to predict possible human metabolites of small molecules including drugs as a sequence translation problem. We innovatively introduced prompt engineering into deep language models to enrich domain knowledge and guide decision-making. The results showed that using prompts that specify the sites of metabolism (SoMs) can steer the model to propose more accurate metabolite predictions, achieving a 30.4% increase in recall and a 16.8% reduction in false positives over the baseline model. The transfer learning strategy was also utilized to tackle the limited availability of metabolic data. For the adaptation to automatic or non-expert prediction, MetaPredictor was designed as a two-stage schema consisting of automatic identification of SoMs followed by metabolite prediction. Compared to four available drug metabolite prediction tools, our method showed comparable performance on the major enzyme families and better generalization that could additionally identify metabolites catalyzed by less common enzymes. The results indicated that MetaPredictor could provide a more comprehensive and accurate prediction of drug metabolism through the effective combination of transfer learning and prompt-based learning strategies.

The augment effects of magnesium hydride on the lipid lowering effect of atorvastatin: an in vivo and in vitro investigation.

There is strong evidence connecting increased serum lipid levels to cardiovascular disorders, including atherosclerosis. Statins is prescribed as the primary medication to decrease lipid levels. Recent research has demonstrated that hydrogen possesses anti-inflammatory and antioxidant properties by modulating the expression of peroxisome proliferator-activated receptor gamma coactivator-1α, ultimately leading to the preservation of lipid homeostasis. Magnesium hydride (MgH2) is a prolonged stable hydrogen storage medium, which can be utilized to investigate its synergistic lipid-lowering effect with statins and its detailed molecular mechanism, both in vivo and in vitro. To ascertain the safety and efficacy of MgH2, we executed a comprehensive research of its influence on both physiological and pathological metrics. We noted a substantial diminution in lipid levels when MgH2 was integrated with atorvastatin, as attested by oil red staining. Furthermore, we scrutinized the regulatory effect of MgH2 on cytochrome P450 3A, which is a metabolic enzyme of statins, and discovered that it could be reduced by the MgH2. Concluding from our results, we propose that MgH2 inhibits the expression of cytochrome P450 3A in the liver and exerts an auxiliary lipid-lowering effect by increasing the blood concentration of statins. By augmenting our comprehension of MgH2's role in ameliorating lipid metabolism, we aspire to develop more promising therapies in the future.

The interaction mechanisms of tetrahydrocurcumin on alcohol dehydrogenase: Insights from enzymatic activity assays, spectroscopic methods and computational techniques

Tetrahydrocurcumin (THC), a major metabolite of curcumin, is renowned for its potent antioxidant and anti-inflammatory properties, including preventing liver injury from alcohol. Alcohol dehydrogenase (ADH), an essential enzyme in alcohol metabolism, is significant in the development of alcohol-induced diseases. Hence, enzymatic activity assays, spectroscopic methods, and computational techniques were employed in this study to explore their interaction. The results indicated that THC can competitively inhibit ADH activity, as inferred from the kinetic parameter values. Meanwhile, THC spontaneously entered the substrate-binding cavity of ADH to form a binary complex, and surrounded by Thr178, Leu57, Ile318, Leu141, Glu68, Leu116, Phe93, Val294, and Asp49. The Ka value of this binding was 1.724 ± 0.017 × 104 M−1 at 298 K. This binding process was driven by hydrogen bonds and van der Waals forces; additionally, the π electrons in THC were significant for the stability of the ADH-THC complex. The presence of THC led to a decrease in the α-helix content of ADH, resulting in a looser secondary structure. Furthermore, molecular dynamic simulations revealed that Glu68, Leu116, Phe93, Val294, and Asp49 made significant contributions to the binding process. The inhibition of ADH catalytic activity may be primarily attributed to the interaction between THC and the Val294 residue.

AT-0174, a novel dual IDO1/TDO2 enzyme inhibitor, synergises with temozolomide to improve survival in an orthotopic mouse model of glioblastoma

BackgroundGlioblastoma is an aggressive brain cancer, usually of unknown etiology, and with a very poor prognosis. Survival from diagnosis averages only 3 months if left untreated and this only increases to 12–15 months upon treatment. Treatment options are currently limited and typically comprise radiotherapy plus a course of the DNA-alkylating chemotherapeutic temozolomide. Unfortunately, the disease invariably relapses after several months of treatment with temozolomide, due to the development of resistance to the drug. Increased local tryptophan metabolism is a feature of many solid malignant tumours through increased expression of tryptophan metabolising enzymes. Glioblastomas are notable for featuring increased expression of the tryptophan catabolizing enzymes indole-2,3-dioxygenase-1 (IDO1), and especially tryptophan-2,3-dioxygenase-2 (TDO2). Increased IDO1 and TDO2 activity is known to suppress the cytotoxic T cell response to tumour cells, and this has led to the proposal that the IDO1 and TDO2 enzymes represent promising immuno-oncology targets. In addition to immune modulation, however, recent studies have also identified the activity of these enzymes is important in the development of resistance to chemotherapeutic agents.MethodsIn the current study, the efficacy of a novel dual inhibitor of IDO1 and TDO2, AT-0174, was assessed in an orthotopic mouse model of glioblastoma. C57BL/6J mice were stereotaxically implanted with GL261(luc2) cells into the striatum and then administered either vehicle control, temozolomide (8 mg/kg IP; five 8-day cycles of treatment every 2 days), AT-0174 (120 mg/kg/day PO) or both temozolomide + AT-0174, all given from day 7 after implantation.ResultsTemozolomide decreased tumour growth and improved median survival but increased the infiltration of CD4+ Tregs. AT-0174 had no significant effect on tumour growth or survival when given alone, but provided clear synergy in combination with temozolomide, further decreasing tumour growth and significantly improving survival, as well as elevating CD8+ T cell expression and decreasing CD4+ Treg infiltration.ConclusionAT-0174 exhibited an ideal profile for adjunct treatment of glioblastomas with the first-line chemotherapeutic drug temozolomide to prevent development of CD4+ Treg-mediated chemoresistance.

An NAD+-dependent metabolic checkpoint regulates hematopoietic stem cell activation and aging.

How hematopoietic stem cells (HSCs) maintain metabolic homeostasis to support tissue repair and regeneration throughout the lifespan is elusive. Here, we show that CD38, an NAD+-dependent metabolic enzyme, promotes HSC proliferation by inducing mitochondrial Ca2+ influx and mitochondrial metabolism in young mice. Conversely, aberrant CD38 upregulation during aging is a driver of HSC deterioration in aged mice due to dysregulated NAD+ metabolism and compromised mitochondrial stress management. The mitochondrial calcium uniporter, a mediator of mitochondrial Ca2+ influx, also supports HSC proliferation in young mice yet drives HSC decline in aged mice. Pharmacological inactivation of CD38 reverses HSC aging and the pathophysiological changes of the aging hematopoietic system in aged mice. Together, our study highlights an NAD+ metabolic checkpoint that balances mitochondrial activation to support HSC proliferation and mitochondrial stress management to enhance HSC self-renewal throughout the lifespan, and links aberrant Ca2+ signaling to HSC aging.

Evolutionary plasticity and functional repurposing of the essential metabolic enzyme MoeA.

MoeA, or gephyrin in higher eukaryotes, is crucial for molybdenum cofactor biosynthesis required in redox reactions. Gephyrin is a moonlighting protein also involved in postsynaptic receptor clustering, a feature thought to be a recent evolutionary trait. We showed previously that a repurposed copy of MoeA (Glp) is involved in bacterial cell division. To investigate how MoeA acquired multifunctionality, we used phylogenetic inference and protein structure analyses to understand the diversity and evolutionary history of MoeA. Glp-expressing Bacteria have at least two copies of the gene, and our analysis suggests that Glp has lost its enzymatic role. In Archaea we identified an ancestral duplication where one of the paralogs might bind tungsten instead of molybdenum. In eukaryotes, the acquisition of the moonlighting activity of gephyrin comprised three major events: first, MoeA was obtained from Bacteria by early eukaryotes, second, MogA was fused to the N-terminus of MoeA in the ancestor of opisthokonts, and finally, it acquired the function of anchoring GlyR receptors in neurons. Our results support the functional versatility and adaptive nature of the MoeA scaffold, which has been repurposed independently both in eukaryotes and bacteria to carry out analogous functions in network organization at the cell membrane.

NAD+ Metabolic Enzyme Inhibitor as Radiosensitizer for Malignant Meningioma and its Modulation of P53 Expression.

Surgical resection followed by radiotherapy (RT) is recommended for malignant meningioma, but poor outcome is unavoidable. To improve the efficacy of RT in malignant meningioma, a targeted radiosensitizer can be added. Nicotinamide phosphoribosyltransferase (NAMPT), highly expressed in high-grade meningiomas, may play a role in determining the radioresponse. Herein, we evaluated the impact of NAMPT inhibition on radiosensitivity in malignant meningioma in vivo and in vitro. IOMM-Lee and TTMM705 cells were treated with NAMPT inhibition (FK866 or shRNA NAMPT) before irradiation. The subsequent clonogenic assay demonstrated significantly increased radiosensitivity. Combination treatment with FK866 and irradiation significantly increased the number of G2/M-phase cells, percentage of apoptotic cells, and γ-H2A.X level compared with FK866 or RT alone. We examined the effect of NAMPT inhibition on NMI and p53 expression in IOMM-Lee and TTMM705 cells. NAMPT inhibition by FK866 and shRNA treatment increased NMI, p53, CDKN1A and BAX expression. Additionally, we assessed the efficacy of FK866/RT combination treatment in vivo. The combination treatment exhibited increased antitumor efficacy compared with either treatment alone. The Ki67 level was significantly lower, and the p53 and γ-H2A.X levels were significantly higher in the combination treatment group than in the other three groups. In conclusion, these results indicate that FK866 improves radiosensitivity in malignant meningioma, an effect that may be attributed to the increase in p53 expression.

The role of acetylation in obesity-induced cardiac metabolic alterations.

Obesity is a growing public health problem, with its prevalence rate having tripled in the last five decades. It has been shown that obesity is associated with alterations in cardiac energy metabolism, which in turn plays a significant role in heart failure development. During obesity, the heart becomes highly dependent on fatty acid oxidation as its primary source of energy (ATP), while the contribution from glucose oxidation significantly decreases. This metabolic inflexibility is associated with reduced cardiac efficiency and contractile dysfunction. Although it is well recognized that alterations in cardiac energy metabolism during obesity are associated with the risk of heart failure development, the molecular mechanisms controlling these metabolic changes are not fully understood. Recently, posttranslational protein modifications of metabolic enzymes have been shown to play a crucial role in cardiac energy metabolic changes seen in obesity. Understanding these novel mechanisms is important in developing new therapeutic options to treat or prevent cardiac metabolic alteration and dysfunction in obese individuals. This review discusses posttranslational acetylation changes during obesity and their roles in mediating cardiac energy metabolic perturbations during obesity as well as its therapeutic potentials.

Systematic Review of Naturally Derived Substances That Act as Inhibitors of the Nicotine Metabolizing Enzyme Cytochrome P450 2A6.

Tobacco smoking has been highlighted as a major health challenge in modern societies. Despite not causing death directly, smoking has been associated with several health issues, such as cardiovascular diseases, respiratory disorders, and several cancer types. Moreover, exposure to nicotine during pregnancy has been associated with adverse neurological disorders in babies. Nicotine Replacement Therapy (NRT) is the most common strategy employed for smoking cessation, but despite its widespread use, NRT presents with low success and adherence rates. This is attributed partially to the rate of nicotine metabolism by cytochrome P450 2A6 (CYP2A6) in each individual. Nicotine addiction is correlated with the high rate of its metabolism, and thus, novel strategies need to be implemented in NRT protocols. Naturally derived products are a cost-efficient and rich source for potential inhibitors, with the main advantages being their abundance and ease of isolation. This systematic review aims to summarize the natural products that have been identified as CYP2A6 inhibitors, validated through in vitro and/or in vivo assays, and could be implemented as nicotine metabolism inhibitors. The scope is to present the different compounds and highlight their possible implementation in NRT strategies. Additionally, this information would provide valuable insight regarding CYP2A6 inhibitors, that can be utilized in drug development via the use of in silico methodologies and machine-learning models to identify new potential lead compounds for optimization and implementation in NRT regimes.

FOXM1 requires IDH1 for late genes expression in mitotic cells.

Isocitrate dehydrogenase 1 (IDH1) is a metabolic enzyme that converts isocitrate to α-ketoglutarate in cells. However, research on IDH1 is more focused on the metabolite D-2-hydroxyglutarate than the cellular roles of the IDH1 protein. Metabolic enzymes can moonlight by participating in diverse cellular processes in cancer cells. This moonlighting function of the metabolic enzymes can contribute to changes in gene expression. It is unknown whether IDH1 associates with any transcription factor. We asked whether IDH1 coordinates with forkhead box protein M1 (FOXM1) in mitotic cells to regulate late genes expression. We found that depletion of IDH1 reduces canonical FOXM1-target expression in mitotic cells. Also, IDH1 binds to FOXM1 and a subset of MuvB proteins, Lin-9 and Lin-54, in mitotic cells. Based on these observations, we suggest that IDH1 coordinates with FOXM1 in mitotic cells to regulate late genes expression.

Enhanced nitrogen and phosphorus removal by iron-manganese mediated autotrophic denitrification in electrochemical system and the underlying mechanisms

At present, the research on Fe/Mn autotrophic denitrification is very limited, and the underlying mechanism in electrochemical system is not clear. In this study, an electrochemical system based on Fe-Mn autotrophic denitrification was constructed for the treatment of low C/N wastewater. The underlying mechanism and electrochemical process of Fe/Mn-mediated autotrophic denitrification were elucidated. The results showed that pyrite and manganese mineral matrix had no significant effect on COD removal, but had significant effect on nitrogen removal. R1 (activated carbon matrix) had the lowest nitrogen removal rate, with an average of 66.06 %. The mean removal rate of R2 (iron matrix) and R3 (manganese matrix) were 93.94 % and 95.89 %, respectively. The coupling of iron/manganese ammoxidation and autotrophic denitrification was the main mechanism to achieve efficient nitrogen removal. ICP and FIRT results showed that strong REDOX reactions of Fe, Mn and sulfur occurred at the anode of MFC. Direct precipitation of iron and manganese and electrochemical flocculation (FeOOH) effectively improved phosphorus removal. The phosphorus removal rates of R2 and R3 reached 93.89 % and 95.85 %, respectively. R3 has high electron transfer efficiency with a maximum voltage of 680 mV. Metagenomic analysis showed that 19 important transcripts associated with nitrogen metabolism pathways and 4 nitrogen metabolism pathways were detected. Enzymes encoded by nap A and nar G genes were abundant in R3 system. Reductase encoded by nrfA and nrfH genes was abundant in R2 system. Iron REDOX genes iroE, iroN, oorA, and manganese REDOX genes moxR, moxA were detected. The results of metabolic pathways and related enzymes further revealed the coupling cycle relationship between metal elements and nitrogen, phosphorus and sulfur in electrochemical systems. This study can not only provide a new method for efficient nitrogen and phosphorus removal of sewage, but also provide scientific basis for improving the geochemical cycle of metal elements and nitrogen elements.

Comparative Transcriptome Analysis Reveals Different Responses in Three Developmental Stages of Mythimna loreyi to Cold Stress.

The loreyi leafworm Mythimna loreyi (Lepidoptera: Noctuidae) is a serious pest of agriculture that causes particular damage to Gramineae crops in Asia, Europe, Australia, Africa, and the Middle East. Low temperature is one of the important environmental factors that limits the survival, distribution, colonization, and abundance of M. loreyi. However, the metabolic synthesis pathways of cold-tolerant substances in M. loreyi and the key genes involved in the regulation under cold stress remain largely unknown. In this study, we sequenced the transcriptomes of three developmental stages (larvae, pupae, and adults) of M. loreyi to discover the molecular mechanisms of their responses to cold stress. In total, sequencing generated 120.64 GB of clean data from 18 samples, of which 19,459 genes and 1740 differentially expressed genes (DEGs) were identified. The enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that many DEGs were mainly enriched in pathways associated with energy metabolism and hormone metabolism. Among these, genes encoding multiple metabolic enzymes, cuticle proteins (CPs), and heat shock proteins (HSPs) were differentially expressed. These results indicate that there are significant differences among the three developmental stages of M. loreyi exposed to cold stress and provide a basis for further studying the molecular mechanisms of cold tolerance in insects.

A Computational Approach of Anti-diabetic Potential Evaluation of Flower and Seed of Nyctanthes arbor tristis Linn

Exploring the medicinal significance of bioactive compounds through computational methods is an increasingly practiced approach in contemporary medicinal research. This study aims to assess the antidiabetic potential of compounds extracted from the plant Nyctanthes arbor tristis by evaluating their ability to inhibit the carbohydrate metabolic enzyme α-glucosidase. The research work was conducted through molecular docking calculation, molecular dynamics simulation (MDS), and ADMET prediction techniques. Among the compounds, arbortistoside-C (NAS03), and arbortristoside-D (NAS04) found in the seed of the plant were identified as hit inhibitors of the target protein with docking scores, -9.9 and -9.4 kcal/mol, respectively. The compounds showed a comparable docking score with the drug of diabetes acarbose (-8.6 kcal/mol). Geometrical parameters like radius of gyration, solvent accessibility surface, root mean square deviation, and root mean square fluctuation from MDS supported the stability of the protein-ligand complex. MMPBSA calculations demonstrated the stability and feasibility of the complex with binding free energy changes of -29.06±6.06 and -23.58±8.80 kcal/mol for compounds NAS03 and NAS04, respectively. The ADMET prediction suggested the drug-likeness of the compounds compared with that of the standard drugs. The results could be used in proposing the antidiabetic potential of the two compounds from the plant as a potential inhibitors of α-glucosidase enzyme. Further, in vitro and in vivo experiments on such compounds could be a more reliable path to validate the output of this computational research.

Host cell CRISPR genomics and modelling reveal shared metabolic vulnerabilities in the intracellular development of Plasmodium falciparum and related hemoparasites

Parasitic diseases, particularly malaria (caused by Plasmodium falciparum) and theileriosis (caused by Theileria spp.), profoundly impact global health and the socioeconomic well-being of lower-income countries. Despite recent advances, identifying host metabolic proteins essential for these auxotrophic pathogens remains challenging. Here, we generate a novel metabolic model of human hepatocytes infected with P. falciparum and integrate it with a genome-wide CRISPR knockout screen targeting Theileria-infected cells to pinpoint shared vulnerabilities. We identify key host metabolic enzymes critical for the intracellular survival of both of these lethal hemoparasites. Remarkably, among the metabolic proteins identified by our synergistic approach, we find that host purine and heme biosynthetic enzymes are essential for the intracellular survival of P. falciparum and Theileria, while other host enzymes are only essential under certain metabolic conditions, highlighting P. falciparum’s adaptability and ability to scavenge nutrients selectively. Unexpectedly, host porphyrins emerge as being essential for both parasites. The shared vulnerabilities open new avenues for developing more effective therapies against these debilitating diseases, with the potential for broader applicability in combating apicomplexan infections.

Effects and mechanisms of kitchen waste organic fertilizers application on soil nitrogen transformation, plant pathogenic virulence genes, and metabolites

The application of organic fertilizers enhances soil fertility and alters the function and structure of the soil microbial communities. When subjected to aerobic composting, kitchen waste is transformed into organic fertilizer. However, the ecological benefits and safety risks of kitchen waste organic fertilizers (OF) in soil require further evaluation. Therefore, this study conducted a pot experiment to investigate the effects and mechanisms of OF application on soil properties, crop growth, nitrogen transformation, plant pathogenic virulence genes, and metabolites. The results indicated that OF treatment promoted vitamin C synthesis in pakchoi (35.23–48.00 %) and reduced soil N2O emissions during cultivation compared with inorganic fertilizer (IF) (65.50–68.08 %) (P<0.01). IF treatment significantly increased the abundance of Rhodanobacter (6.41 %) and Nitrobacter (3.16 %), leading to increased N2O emissions (17.94 mg kg−1). Key nitrogen metabolism enzymes and functional genes indicated that nitrification and denitrification pathways were the primary contributors to N2O production. Metagenomic results revealed that IF treatment enhanced virulence gene pathogenicity through quorum sensing (QS), whereas OF treatment reduced virulence gene accumulation in plant pathogenic bacteria. Metabolomic analysis demonstrated that OF treatment significantly upregulated substances beneficial to soil activity and plant growth, while inhibiting pollutant expression. PLS-PM results indicated that soil properties played a pivotal role in shaping the intricate relationships among microbial communities, functional genes, and substance metabolism. This study demonstrated that OF application contributed to the promotion of plant health and optimization of soil ecosystems, thereby providing theoretical support for the further expansion of OF applications in agriculture.

Enhanced removal of PHE-Cd2+ co-contamination by the mixed bacterial cultures of Pseudomonas putida and Arthrobacter sp.: Performance and mechanism

The strain species resource is essential for microbial remediation of PHE (phenanthrene)-Cd2+ co-contamination. In this study, the mixed bacterial culture (M) was established to intensively remediate PHE-Cd2+ co-contamination using PAHs-degrading bacteria Pseudomonas putida and Arthrobacter sp. with different Cd2+ tolerance. The PHE degradation efficiency of the mixed bacterial cultures (M) was 65 %-81 % under different Cd2+ concentration of 10–50 mg/L, respectively, which was 1.40–2.98 times that of the individual strains. In addition, strain metabolic enzyme activity, intracellular structure and extracellular polymeric substances (EPS) were carried out under Cd2+ stress. Results showed that the catechol 1,2-dioxygenase enzyme (C120) and the electron transport system activity (ETSA) were less adversely affected by Cd2+ in mixed bacterial cultures. Transmission electron microscopy images showed that the cells surface of the mixed bacterial cultures (M) could be adsorbed more Cd2+ compared to the single strain. The analysis of cell functional groups suggested that C-O-C and C-O groups in EPS mediated the removal of Cd2+ in the mixed bacterial culture. Moreover, the Cd2+ removal proportion by EPS adsorption of the mixed bacterial cultures accounted for 92 %, 67 %, 57 %, and 52 % under Cd2+ stress of 0.5, 10, 25, and 50 mg/L, respectively, which were superior to that of individual strains. This study confirmed the potential application and technical reference of the specific mixed bacterial cultures in the enhanced bioremediation of PHE-Cd2+ co-contamination.

Drug interaction with UDP-Glucuronosyltransferase (UGT) enzymes is a predictor of drug-induced liver injury.

DILI frequently contributes to the attrition of new drug candidates and is a common cause for the withdrawal of approved drugs from the market. Although some noncytochrome P450 (non-CYP) metabolism enzymes have been implicated in DILI development, their association with DILI outcomes has not been systematically evaluated. In this study, we analyzed a large data set comprising 317 drugs and their interactions in vitro with 42 non-CYP enzymes as substrates, inducers, and/or inhibitors retrieved from historical regulatory documents using multivariate logistic regression. We examined how these in vitro drug-enzyme interactions are correlated with the drugs' potential for DILI concern, as classified in the Liver Toxicity Knowledge Base database. Our study revealed that drugs that inhibit non-CYP enzymes are significantly associated with high DILI concern. Particularly, interaction with UDP-glucuronosyltransferases (UGT) enzymes is an important predictor of DILI outcomes. Further analysis indicated that only pure UGT inhibitors and dual substrate inhibitors, but not pure UGT substrates, are significantly associated with high DILI concern. Drug interactions with UGT enzymes may independently predict DILI, and their combined use with the rule-of-two model further improves overall predictive performance. These findings could expand the currently available tools for assessing the potential for DILI in humans.

Targeted-metabolomic and untargeted-proteomic approaches reveal the effects of muscle fibre type and postmortem ageing on taste-active compounds in beef

The taste of beef is caused by taste-active compounds detected in the mouth during mastication. We hypothesised that the concentration of taste-active compounds in beef is influenced by muscle-fibre-type and postmortem ageing. To test this, and unravel the underlying mechanisms, we investigated the taste-active compounds, and proteomic profiles, in beef masseter [oxidative muscle, all type I fibres) and cutaneous trunci (glycolytic muscle, mostly type II fibres) before and after 14-days postmortem ageing. Our results showed that nucleotides were initially higher and degraded slower in cutaneous trunci (P < 0.05 for both), which could be explained by the profile of nucleotide metabolism enzymes. In contrast, free amino acids were initially higher and increased more in masseter compared to cutaneous trunci (P < 0.05 for all), which might be explained by the profile and activity of proteases in these two muscles. Our results indicate the taste of beef is affected by the muscle-fibre-type and postmortem ageing.

Ribosome External Electric Field Regulates Metabolic Enzyme Activity: The RAMBO Effect.

Ribosomes bind to many metabolic enzymes and change their activity. A general mechanism for ribosome-mediated amplification of metabolic enzyme activity, RAMBO, was formulated and elucidated for the glycolytic enzyme triosephosphate isomerase, TPI. The RAMBO effect results from a ribosome-dependent electric field-substrate dipole interaction energy that can increase or decrease the ground state of the reactant and product to regulate catalytic rates. NMR spectroscopy was used to determine the interaction surface of TPI binding to ribosomes and to measure the corresponding kinetic rates in the absence and presence of intact ribosome particles. Chemical cross-linking and mass spectrometry revealed potential ribosomal protein binding partners of TPI. Structural results and related changes in TPI energetics and activity show that the interaction between TPI and ribosomal protein L11 mediate the RAMBO effect.