Microcoulometric analysis of trimethylamine dehydrogenase.
Ontology highlight
ABSTRACT:
SUBMITTER: Barber MJ
PROVIDER: S-EPMC1135459 | biostudies-other | 1988 Dec
REPOSITORIES: biostudies-other
Similar Datasets
Project description:1. The trimethylamine dehydrogenase of bacterium 4B6 was purified to homogeneity as judged by analytical polyacrylamide-gel electrophoresis. The specific activity of the purified enzyme is 30-fold higher than that of crude sonic extracts. 2. The molecular weight of the enzyme is 161000. 3. The kinetic properties of the purified enzyme were studied by using an anaerobic spectrophotometric assay method allowing the determination of trimethylamine dehydrogenase activity at pH8.5, the optimum pH. The apparent K(m) for trimethylamine is 2.0+/-0.3mum and the apparent K(m) for the primary hydrogen acceptor, phenazine methosulphate, is 1.25mm. 4. Of 13 hydrogen acceptors tested, only Brilliant Cresyl Blue and Methylene Blue replace phenazine methosulphate. 5. A number of secondary and tertiary amines with N-methyl and/or N-ethyl groups are oxidized by the purified enzyme; primary amines and quaternary ammonium salts are not oxidized. Of the compounds that are oxidized by the purified enzyme, only trimethylamine and ethyldimethylamine support the growth of bacterium 4B6. 6. Trimethylamine dehydrogenase catalyses the anaerobic oxidative N-demethylation of trimethylamine with the formation of stoicheiometric amounts of dimethylamine and formaldehyde. Ethyldimethylamine is also oxidatively N-demethylated yielding ethylmethylamine and formaldehyde; diethylamine is oxidatively N-de-ethylated. 7. The activity of the purified enzyme is unaffected by chelating agents and carbonyl reagents, but is inhibited by some thiol-binding reagents and by Cu(2+), Co(2+), Ni(2+), Ag(+) and Hg(2+). Trimethylamine dehydrogenase activity is potently inhibited by trimethylsulphonium chloride, by tetramethylammonium chloride and other quaternary ammonium salts, and by monoamine oxidase inhibitors of the substituted hydrazine and the non-hydrazine types. 8. Inhibition by the substituted hydrazines is time-dependent, is prevented by the presence of trimethylamine or trimethylamine analogues and in some cases requires the presence of the hydrogen acceptor phenazine methosulphate. The inhibition was irreversible with the four substituted hydrazines that were tested.
| S-EPMC1168424 | biostudies-other
Project description:Trimethylamine dehydrogenases from bacterium W3A1 and Hyphomicrobium X and the dimethylamine dehydrogenase from Hyphomicrobium X were found to contain only one kind of subunit. The millimolar absorption coefficient of a single [4Fe-4S] cluster in trimethylamine dehydrogenase from bacterium W3A1 was estimated to be 14.8 mM-1 . cm-1 at 443 nm. From this value a 1:1 stoicheiometry of the prosthetic groups, 6-S-cysteinyl-FMN and the [4Fe-4S] cluster, was established. Millimolar absorption coefficients of the three enzymes were in the range 49.4-58.7 mM-1 . cm-1 at approx. 440 nm. This range of values is consistent with the presence of two [4Fe-4S] clusters and two flavin residues, for which the millimolar absorption coefficient had earlier been found to be 12.3 mM-1 . cm-1 at 437 nm. The N-terminal amino acid was alanine in each of the three enzymes. Sequence analysis of the first 15 residues from the N-terminus of dimethylamine dehydrogenase indicated a single unique sequence. Two identical subunits, each containing covalently bound 6-S-cysteinyl-FMN and a [4Fe-4S] cluster, in each of the enzymes are therefore indicated.
| S-EPMC1154397 | biostudies-other
Project description:Trimethylaminuria (TMAU) is a genetic disorder whereby people cannot convert trimethylamine (TMA) to its oxidized form (TMAO), a process that requires the liver enzyme FMO3. Loss-of-function variants in the FMO3 gene are a known cause of TMAU. In addition to the inability to metabolize TMA precursors like choline, patients often emit a characteristic odor because while TMAO is odorless, TMA has a fishy smell. The Monell Chemical Senses Center is a research institute with a program to evaluate people with odor complaints for TMAU.Here we evaluated ten subjects by (1) odor evaluation by a trained sensory panel, (2) analysis of their urine concentration of TMA relative to TMAO before and after choline ingestion, and (3) whole exome sequencing as well as subsequent variant analysis of all ten samples to investigate the genetics of TMAU.While all subjects reported they often emitted a fish-like odor, none had this malodor during sensory evaluation. However, all were impaired in their ability to produce >90% TMAO/TMA in their urine and thus met the criteria for TMAU. To probe for genetic causes, the exome of each subject was sequenced, and variants were filtered by genes with a known (FMO3) or expected effect on TMA metabolism function (other oxidoreductases). We filtered the remaining variants by allele frequency and predicated functional effects. We identified one subject that had a rare loss-of-function FMO3 variant and six with more common decreased-function variants. In other oxidoreductases genes, five subjects had four novel rare single-nucleotide polymorphisms as well as one rare insertion/deletion. Novel in this context means no investigators have previously linked these variants to TMAU although they are in dbSNP.Thus, variants in genes other than FMO3 may cause TMAU and the genetic variants identified here serve as a starting point for future studies of impaired TMA metabolism.
| S-EPMC5310055 | biostudies-literature
Project description:Bacterial trimethylamine dehydrogenase contains a novel type of covalently bound flavin mononucleotide and a tetrameric iron-sulphur centre. The dehydrogenase takes up 1.5mol of dithionite/mol of enzyme and is thereby converted into the flavin quinol-reduced (4Fe-4S) form, with the expected bleaching of the visible absorption band of the flavin and the emergence of signals of typical reduced ferredoxin in the electronparamagnetic-resonance spectrum. On reduction with a slight excess of substrate, however, unusual absorption and electron-paramagnetic-resonance spectra appear quite rapidly. The latter is attributed to extensive interaction between the reduced (4Fe-4S) centre and the flavin semiquinone. The species of enzyme arising during the catalytic cycle were studied by a combination of rapid-freeze e.p.r. and stopped-flow spectophotometry. The initial reduction of the flavin to the quinol form is far too rapid to be rate-limiting in catalysis, as is the reoxidation of the substrate-reduced enzyme by phenazine methosulphate. Formation of the spin-spin-interacting species from the dihydroflavin is considerably slower, however, and it may be the rate-limiting step in the catalytic cycle, since its rate of formation agrees reasonably well with the catalytic-centre activity determined in steady-state kinetic assays. In addition to the interacting form, a second form of the enzyme was noted during reduction by trimethylamine, differing in absorption spectrum, the structure of which remains to be determined.
| S-EPMC1184175 | biostudies-other
Project description:BACKGROUND:Previous clinical studies have suggested that trimethylamine-N-oxide (TMAO) could contribute to the development of atherosclerosis cardiovascular disease. However, the synthetic analysis in coronary heart disease (CHD) was not yet performed. We aimed to clarify the relationship between elevated plasma concentrations of TMAO and the incidence of major adverse cardiovascular events (MACE) in CHD patients. METHODS:Meta-analysis and dose-response analysis of hazard ratio data from prospective observational studies reporting on the association between TMAO plasma concentrations and the incidence of MACE in patients with CHD were conducted. RESULTS:Of the 2369 published articles identified in the search, seven papers, with data from nine cohort studies (10,301 patients), were included in the meta-analysis. Combined data showed that elevated plasma TMAO concentrations could increase 58% higher risk of MACE in patients with CHD (hazard ratios [HR]: 1.58; 95% confidence interval [CI] = 1.35-1.84, P = 0.000). For follow-up ≥ 1 year, it was associated with 62% higher risk of MACE in patients with longer-term than shorter-term (HR for follow-up ≥ 4 years: 1.96; 95% CI = 1.52-2.52 vs one to 3 years: 1.34; 95% CI = 1.26-1.43, P = 0.004). The dose-response analysis revealed a 'J' shaped association between TMAO concentration and the incidence of MACE (P = 0.033), with the concentration above 5.1 μmol/L being associated with HR of > 1. CONCLUSIONS:Elevated levels of TMAO are associated with an increased incidence of MACE in patients with CHD. TMAO concentration of 5.1 μmol/L may be a cut-off value for prognosis.
| S-EPMC6953212 | biostudies-literature
Project description:Trimethylamine-N-oxide (TMAO), a derivative from the gut microbiota metabolite trimethylamine (TMA), has been identified to be an independent risk factor for promoting atherosclerosis. Evidences suggest that berberine (BBR) could be used to treat obesity, diabetes and atherosclerosis, however, its mechanism is not clear mainly because of its poor oral bioavailability. Here, we show that BBR attenuated TMA/TMAO production in the C57BL/6J and ApoE KO mice fed with choline-supplemented chow diet, and mitigated atherosclerotic lesion areas in ApoE KO mice. Inhibition of TMA/TMAO production by BBR-modulated gut microbiota was proved by a single-dose administration of d9-choline in vivo. Metagenomic analysis of cecal contents demonstrated that BBR altered gut microbiota composition, microbiome functionality, and cutC/cntA gene abundance. Furthermore, BBR was shown to inhibit choline-to-TMA conversion in TMA-producing bacteria in vitro and in gut microbial consortium from fecal samples of choline-fed mice and human volunteers, and the result was confirmed by transplantation of TMA-producing bacteria in mice. These results offer new insights into the mechanisms responsible for the anti-atherosclerosis effects of BBR, which inhibits commensal microbial TMA production via gut microbiota remodeling.
| S-EPMC8052457 | biostudies-literature
Project description:Elevated circulating trimethylamine N-oxide (TMAO) concentrations have been observed in patients with chronic kidney disease (CKD). We aimed to systematically estimate and quantify the association between TMAO concentrations and kidney function. The PubMed, EMBASE, Cochrane Library, Scopus, and Web of Science databases were systematically searched from 1995 to 1 June, 2020, for clinical studies on circulating TMAO concentrations and kidney function indicators. We used R software to conduct meta-analyses of the extracted data. A cumulative meta-analysis was applied to test whether health status affected the pooled effect value. Meta-regression and subgroup analyses were performed to identify possible sources of heterogeneity. Ultimately, we included a total of 32 eligible clinical studies involving 42,062 participants. In meta-analyses of continuous-outcome variables, advanced CKD was associated with a 67.9 μmol/L (95% CI: 52.7, 83.2; P < 0.01) increase in TMAO concentration, and subjects with high concentrations of TMAO had a 12.9 mL/(min·1.73 m2) (95% CI: -16.6, -9.14; P < 0.01) decrease in glomerular filtration rate (GFR). In meta-analyses of the correlations, TMAO was strongly inversely correlated with GFR [Fisher's z-transformed correlation coefficient (ZCOR): -0.45; 95% CI: -0.58, -0.32; P < 0.01] and positively associated with the urine albumin-to-creatinine ratio (UACR; ZCOR: 0.26; 95% CI: 0.08, 0.43; P < 0.01), serum creatinine (sCr; ZCOR: 0.43; 95% CI: 0.28, 0.58; P < 0.01), urine albumin excretion rate (UAER; ZCOR: 0.06; 95% CI: 0.04, 0.09; P < 0.01), blood urea (ZCOR: 0.50; 95% CI: 0.29, 0.72; P < 0.01), blood uric acid (ZCOR: 0.32; 95% CI: 0.25, 0.38; P < 0.01), and serum cystatin C (CysC; ZCOR: 0.47, 95% CI: 0.44, 0.51; P < 0.01). This is the first systematic review and meta-analysis to reveal a negative association between circulating TMAO concentrations and kidney function.
| S-EPMC8321840 | biostudies-literature
Project description:BackgroundTrimethylamine N-oxide (TMAO), a diet-derived, gut microbial-host cometabolite, has been linked to cardiometabolic diseases. However, the relations remain unclear between diet, TMAO, and cardiometabolic health in general populations from different regions and ethnicities.ObjectivesTo examine associations of circulating TMAO with dietary and cardiometabolic factors in a pooled analysis of 16 population-based studies from the United States, Europe, and Asia.MethodsIncluded were 32,166 adults (16,269 white, 13,293 Asian, 1247 Hispanic/Latino, 1236 black, and 121 others) without cardiovascular disease, cancer, chronic kidney disease, or inflammatory bowel disease. Linear regression coefficients (β) were computed for standardized TMAO with harmonized variables. Study-specific results were combined by random-effects meta-analysis. A false discovery rate <0.10 was considered significant.ResultsAfter adjustment for potential confounders, circulating TMAO was associated with intakes of animal protein and saturated fat (β = 0.124 and 0.058, respectively, for a 5% energy increase) and with shellfish, total fish, eggs, and red meat (β = 0.370, 0.151, 0.081, and 0.056, respectively, for a 1 serving/d increase). Plant protein and nuts showed inverse associations (β = -0.126 for a 5% energy increase from plant protein and -0.123 for a 1 serving/d increase of nuts). Although the animal protein-TMAO association was consistent across populations, fish and shellfish associations were stronger in Asians (β = 0.285 and 0.578), and egg and red meat associations were more prominent in Americans (β = 0.153 and 0.093). Besides, circulating TMAO was positively associated with creatinine (β = 0.131 SD increase in log-TMAO), homocysteine (β = 0.065), insulin (β = 0.048), glycated hemoglobin (β = 0.048), and glucose (β = 0.023), whereas it was inversely associated with HDL cholesterol (β = -0.047) and blood pressure (β = -0.030). Each TMAO-biomarker association remained significant after further adjusting for creatinine and was robust in subgroup/sensitivity analyses.ConclusionsIn an international, consortium-based study, animal protein was consistently associated with increased circulating TMAO, whereas TMAO associations with fish, shellfish, eggs, and red meat varied among populations. The adverse associations of TMAO with certain cardiometabolic biomarkers, independent of renal function, warrant further investigation.
| S-EPMC8106754 | biostudies-literature
Project description:High hydrostatic pressure (HHP) is a characteristic environmental factor of the deep ocean. However, it remains unclear how piezotolerant bacteria adapt to HHP. Here, we identify a two-step metabolic pathway to cope with HHP stress in a piezotolerant bacterium. Myroides profundi D25T, obtained from a deep-sea sediment, can take up trimethylamine (TMA) through a previously unidentified TMA transporter, TmaT, and oxidize intracellular TMA into trimethylamine N-oxide (TMAO) by a TMA monooxygenase, MpTmm. The produced TMAO is accumulated in the cell, functioning as a piezolyte, improving both growth and survival at HHP. The function of the TmaT-MpTmm pathway was further confirmed by introducing it into Escherichia coli and Bacillus subtilis Encoded TmaT-like and MpTmm-like sequences extensively exist in marine metagenomes, and other marine Bacteroidetes bacteria containing genes encoding TmaT-like and MpTmm-like proteins also have improved HHP tolerance in the presence of TMA, implying the universality of this HHP tolerance strategy in marine Bacteroidetes.
| S-EPMC7997507 | biostudies-literature
Project description:The human gut microbiome and its metabolite Trimethylamine N-oxide (TMAO) are sensitive to the human diet and are involved in the complex pathomechanisms that underpin diabetes, obesity, and cardiovascular diseases. A potential involvement of increased TMAO in atrial fibrillation (AF) manifestation and progression is not clear. We measured TMAO in peripheral blood of 45 AF patients and 20 non-AF individuals (matched for age, sex, BMI, prevalence of hypertension and diabetes). TMAO levels in AF (median [IQR] 3.5 µM [2.51-4.53]) were comparable with those in non-AF individuals (3.62 µM [2.49-5.46]) (p = 0.629). There was no association between TMAO and AF progression phenotypes (p = 0.588). In 35 AF patients, TMAO was additionally measured 12-18 months after AF catheter ablation. TMAO levels at baseline and follow-up were correlated (r = 0.481, p = 0.003), and TMAO was increased independent from the success (restoration of sinus rhythm) of the ablation procedure. The data of this pilot study indicate that TMAO is not generally higher in AF and is not associated with AF progression phenotypes. The observed TMAO increase 12-18 months after AF catheter ablation needs further investigation in a larger cohort.
| S-EPMC7452421 | biostudies-literature