Trimethylamine Metabolism Research Articles

Investigations on the effects of rape oil quality, choline and methionine concentration in diets for laying hens on the trimethylamine content of the eggs, on trimethylamine metabolism and on laying performance

An experiment was conducted to study the effects of graded levels of choline addition (0, 500, 1000 and 4000 mg/kg diet) in laying hen diets prepared either with degummed or refined rape oil on the performance, sensory properties and trimethylamine (TMA) contents of the eggs. Furthermore, the diets containing no supplemented choline or 4000 mg choline/kg diet were tested with adequate or inadequate methionine supply (4.2 vs. 2.8 g methionine/kg diet). TMA metabolism and N-balance were measured for the latter diet types, but only with the diets containing refined rape oil. Therefore, a total of 12 and 4 diets were tested in the feeding (n = 60) and balance study (n = 9). Laying performance (23 – 75 weeks of age) was not significantly influenced by increasing choline additions with the exception of feed-to-egg mass ratio which decreased significantly linearly (p linear = 0.003). However, a significant interaction between choline addition and laying month was detected which was caused by a depression of performance of the unsupplemented control group occurring from the sixth laying month. The most obvious effect of an inadequate methionine supply was a temporary drop in performance between the third and sixth laying months. The mean TMA-concentration in pooled egg yolks [μg/g] increased with dietary choline concentration [mg/kg] in an exponentially related fashion (y = 1.14 + 4E−10 ċ x2.71, r2 = 0.962) and suggested only a minor influence of total dietary choline on TMA content up to approximately 2000 mg choline/kg. Individual TMA-concentrations varied greatly from 0.4 – 1.5 μg/g, from 2.2 – 34 μg/g and from 18.4 – 75 μg/g for eggs with a normal, aberrant and heavily aberrant odour, respectively. It is concluded that a total choline concentration of at least approximately 1500 mg/kg is necessary to maintain a maximal laying performance. An inadequate methionine supply cannot be compensated by an increased addition of choline. Neither degummed nor refined rape oil influenced the TMA content of eggs.

A novel denitrifying bacterial isolate that degrades trimethylamine both aerobically and anaerobically via two different pathways.

The aerobic and anaerobic degradation of trimethylamine by a newly isolated denitrifying bacterium from an enrichment culture with trimethylamine inoculated with activated sludge was studied. Based on 16S rDNA analysis, this strain was identified as a Paracoccus sp. The isolate, strain T231, aerobically degraded trimethylamine, dimethylamine and methylamine and released a stoichiometric amount of ammonium ion into the culture fluid as a metabolic product, indicating that these methylated amines were completely degraded to formaldehyde and ammonia. The strain degraded trimethylamine also under denitrifying conditions and consumed a stoichiometric amount of nitrate, demonstrating that complete degradation of trimethylamine was coupled with nitrate reduction. Cell-free extract prepared from cells grown aerobically on trimethylamine exhibited activities of trimethylamine mono-oxygenase, trimethylamine N-oxide demethylase, dimethylamine mono-oxygenase, and methylamine mono-oxygenase. Cell-free extract from cells grown anaerobically on trimethylamine and nitrate exhibited activities of trimethylamine dehydrogenase and dimethylamine dehydrogenase. These results indicate that strain T231 had two different pathways for aerobic and anaerobic degradation of trimethylamine. This is a new feature for trimethylamine metabolism in denitrifying bacteria.

The Suncus (Suncus murinus) Shows Poor Metabolic Phenotype for Trimethylamine N-Oxygenation

In vitro and in vivo N-oxygenation of trimethylamine (TMA) in the suncus (Suncus murinus) was investigated. The N-oxygenation of TMA has been thought to be catalyzed by flavin-containing monooxygenase (FMO). In a previous study, we found that the levels of mRNAs for FMOs were extremely low in the suncus. Thus, we intended to evaluate the capacity of the suncus to N-oxygenate TMA compared to the rat. Eadie–Hofstee plots of the TMA N-oxygenation by suncus liver microsomes showed a biphasic pattern, suggesting that more than two enzymes were involved in this reaction. The low Km component in the suncus showed a twofold higher Km (55 vs. 31 μM) and a fourfold lower Vmax (0.61 vs 2.5 nmol/min/mg protein) values than those obtained using rat liver microsomes, resulting in a sevenfold lower Vmax/Km (11 vs 82 μl/min/mg protein) value. After an intraperitoneal administration of TMA (10 mg/kg body wt), the suncus excreted 39.6% of the dose in 24-h urine as TMA, whereas the rats excreted 6.3%. Metabolic ratio in the TMA N-oxygenation was 1.42 and 0.11 in the suncus and the rat, respectively. These results indicate that the suncus can be an animal model for a poor metabolizer phenotype in TMA metabolism.

Human flavin-containing monooxygenase form 3: cDNA expression of the enzymes containing amino acid substitutions observed in individuals with trimethylaminuria.

Trimethylaminuria is an autosomal recessive human disorder affecting a small part of the population as an inherited polymorphism. Individuals diagnosed with trimethylaminuria excrete relatively large amounts of trimethylamine in their urine, sweat, and breath, and this results in a fishy odor characteristic of trimethylamine. Activity of the human flavin-containing monooxygenase (FMO) has been proposed to be deficient in trimethylaminuria patients causing a decrease in the metabolism of trimethylamine that results in a fishy body odor. Cohorts of Australian, American, and British individuals suffering from trimethylaminuria have been identified. The human FMO3 cDNA was amplified from lymphocytes of affected patients. We report preliminary evidence of substitutions detected by screening of the cDNA and genomic DNA. The variant human FMO3 cDNA was constructed from wild type human FMO3 cDNA by site-directed mutagenesis as maltose-binding protein fusions. Five distinct human FMO3 mutants were expressed as fusion proteins in Escherichia coli and compared with wild type human FMO3 maltose-binding proteins (FMO3-MBP) for the N-oxygenation of 10-[(N,N-dimethylamino)pentyl]-2-(trifluoromethyl)phenothiazine, tyramine, and trimethylamine. Human Lys158 FMO3-MBP and, to a greater extent, human Glu158 FMO3-MBP efficiently N-oxygenated the three amine substrates. Human Lys158 Ile66 FMO3-MBP, Glu158 Ile66 FMO3-MBP, Lys158 Leu153 FMO3-MBP, and Glu158 Leu153 FMO3-MBP were all constructed as mutants identified as possible FMO3 variants responsible for trimethylaminuria and were found to be inactive as N-oxygenases. The results suggest that mutations at codons 66 and 153 of FMO3 can cause trimethylaminuria in humans. We observed a common polymorphism of Lys to Glu at codon 158 of FMO3 that segregated with almost equal allele frequencies in a number of control Australian and North American samples studied. The Lys158 to Glu158 human FMO3 polymorphism does not decrease trimethylamine N-oxygenation for the cDNA-expressed enzyme and thus does not appear to be causative of trimethyaminuria. The data show that the functional activity of human FMO3 can be significantly altered by amino acid changes that have been observed in individuals with clinically diagnosed trimethylaminuria.

Trimethylamine N-oxidation in Turkish women with bacterial vaginosis.

Bacterial vaginosis (BV) is the most common cause of vaginal discharge in women of child-bearing age. A common symptom of this condition is a fishy-smelling vaginal discharge. Trimethylamine (TMA) is the substance which is primarily responsible for this distinctive odour. The ability to metabolize TMA is polymorphically distributed such that the majority of individuals metabolize a large part of the body burden of TMA to the odourless trimethylamine N-oxide (TMAO) which is excreted in urine with a small amount of TMA. However, in certain individuals, N-oxidation of TMA is impaired which results in the excretion of large amounts of TMA in the urine, breath, sweat and vaginal secretions. In the present study the metabolism of TMA to TMAO was determined in women with clinically diagnosed BV, women with fishy-smelling vaginal discharge but with no other evidence of BV and control women with no evidence of fishy-smelling vaginal discharge. An index of TMA N-oxidation was established for all subjects after analysis of a 24 h urine sample for free TMA and total TMA after reduction of TMAO. We show that, irrespective of diagnosis of BV or not, women with fishy-smelling vaginal discharge excrete significantly more free TMA and have a similarly significantly reduced capacity to N-oxidize TMA when compared to healthy control women. Thus, the results of this study suggest that a woman's ability to metabolize TMA to TMAO is an important factor which predisposes to a fishy-smelling vaginal discharge.

Trimethylamine N-oxygenation and N-demethylation in rat liver microsomes

The in vitro oxidation of trimethylamine (TMA) to TMA N-oiade (TMAO) and dimethyl-amine (DMA) was studied in rat liver microsomes. Pretreatment of rats with phenobarbital, 3-methyl-cholanthrene, ethanol or pregnenolone 16α-carbonitrile had little or no effect on the liver microsomal metabolism of TMA to TMAO or DMA. Changing the atmosphere in the incubation vessel from 20% oxygen/80% nitrogen (air) to 100% oxygen had a selective stimulatory effect on the N-oxygenation of TMA but did not affect TMA N-demethylation. In addition, the K m for TMA N-demethylation was 5-fold higher than for the N-oxygenation reaction. The results of these studies suggest that the enzyme systems responsible for N-demethylation and N-oxygenation are different and that they are under different regulatory control. Carbon monoxide ( CO/O 2 = 80 20 ) had little or no inhibitory effect on either the N-demethylation or N-oxygenation of TMA by liver chromosomes from control or pregnenolone 16α-carbonitrile-treated rats. Additional studies indicated that methimazole, an inhibitor of FAD-containing monooxygenase (FMO), was a potent inhibitor of TMA oxidation. Preincubation of liver microsomes from control or pregnenolone 16α-carbonitrile-treated rats at 37° for 10 min without NADP(H) (a procedure that irreversibly inactivated FMO activity) resulted in > 95% inhibition of TMA N-demethylation and N-oxygenation, and this inhibition was prevented by including a NADPH-generating system in the preincubation medium (a procedure for preventing the thermal inactivation of FMO activity). The data suggest that FMOs are the major enzymes responsible for N-demethylation and N-oxygenation of TMA in rat liver microsomes.

Microbial metabolism of C 1-nitrogen compounds other than cyanide

The following topics are discussed in this review: the structure of methylamine dehydrogenase and the binding of its pyrrolo-quinoline quinone (PQQ) prosthetic group, the role of the copper protein amicyanin as electron acceptor of the enzyme and the nature of the electron carriers between amicyanin and oxygen in the electron transport chain. Also covered are recent developments in the metabolism of trimethylamine and its N-oxide and N-methylformamides.

Microbial metabolism of C1-nitrogen compounds other than cyanide

The following topics are discussed in this review: the structure of methylamine dehydrogenase and the binding of its pyrrolo-quinoline quinone (PQQ) prosthetic group, the role of the copper protein amicyanin as electron acceptor of the enzyme and the nature of the electron carriers between amicyanin and oxygen in the electron transport chain. Also covered are recent developments in the metabolism of trimethylamine and its N-oxide and N-methylformamides.

Nitrogen metabolism in the facultative methylotroph Arthrobacter P1 grown with various amines or ammonia as nitrogen sources.

The metabolism of trimethylamine (TMA) and dimethylamine (DMA) in Arthrobacter P1 involved the enzymes TMA monooxygenase and trimethylamine-N-oxide (TMA-NO) demethylase, and DMA monooxygenase, respectively. The methylamine and formaldehyde produced were further metabolized via a primary amine oxidase and the ribulose monophosphate (RuMP) cycle. The amine oxidase showed activity with various aliphatic primary amines and benzylamine. The organism was able to use methylamine, ethylamine and propylamine as carbon- and nitrogen sources for growth. Butylamine and benzylamine only functioned as nitrogen sources. Growth on glucose with ethylamine, propylamine, butylamine and benzylamine resulted in accumulation of the respective aldehydes. In case of ethylamine and propylamine this was due to repression by glucose of the synthesis of the aldehyde dehydrogenase(s) required for their further metabolism. Growth on glucose/methylamine did not result in repression of the RuMP cycle enzyme hexulose-6-phosphate synthase (HPS). High levels of this enzyme were present in the cells and as a result formaldehyde did not accumulate. Ammonia assimilation in Arthrobacter P1 involved NADP-dependent glutamate dehydrogenase (GDH), NAD-dependent alanine dehydrogenase (ADH) and glutamine synthetase (GS) as key enzymes. In batch cultures both GDH and GS displayed highest levels during growth on acetate with methylamine as the nitrogen source. A further increase in the levels of GS, but not GDH, was observed under ammonia-limited growth conditions in continuous cultures with acetate or glucose as carbon sources.

Metabolism of trimethylamines in kelp bass (Paralabrax clathratus) and marine and freshwater pink salmon (Oncorhynchus gorbuscha).

3H or 14C labeled tracers were used to investigate the metabolism of trimethylamine (TMA), trimethylamine oxide (TMAO), choline, and betaine in free swimming kelp bass (Paralabrax clathratus). An indwelling cannula in the ventral aorta was used to administer tracer and with-draw blood samples. The concentrations of TMA and TMAO were determined in liver, muscle, and plasma. The TMA liver content is higher than that of muscle (0.85 vs less than 0.01 mumoles/g wet tissue) while the amount of TMAO in muscle greatly exceeds its liver concentration (60 vs 0.04 mumoles/g wet tissue). Prolonged fasting (21 and 75 days) or feeding the fish a squid diet containing high levels of TMAO did not alter the tissue concentrations of TMA or TMAO, suggesting that these compounds are endogenous in origin and that their tissue concentrations are subject to regulation. Comparison of the radiospecific activities of TMA and TMAO, and the administered TMA tracer suggest that TMA is channeled directly to TMAO in the liver without equilibration in the hepatic TMA pool. The conversion kinetics of TMA to TMAO and the distribution of these amines in liver and muscle with time suggest that labeled TMA is rapidly taken up into a sequestered pool from which it is slowly released, oxidized to TMAO in the liver, and then transported via the circulation to the muscle mass. The location of this proposed sequestered TMA pool was not determined. Experiments with labeled choline and betaine suggest that these compounds are interconverted in the liver and that enzymes are present for conversion of choline in equilibrium betaine----TMA----TMAO. Labeled dimethylamine (DMA) was not metabolized and is, therefore, probably not a precursor of TMA and TMAO. [14C]Trimethylamine (TMA) was also used to investigate the possible role of trimethylamine oxide (TMAO) as an osmoregulatory compound in migrating prespawning cannulated Pacific pink salmon (Oncorhynchus gorbuscha) taken from marine or fresh water environments. Marine and fresh water salmon oxidized administered [14C]TMA to TMAO; labeled metabolites other than TMA and TMAO were not detected. Four hours after [14C]TMA injection about 10% of the administered dose was present in muscle as labeled TMAO and about 33% as TMA. Unlike our finding in kelp bass, [14C]TMAO was not recovered in liver, although low amounts of labeled TMA were found (0.4% of administered dose). Labeled TMA and TMAO, however, were detected in liver after [14C]betaine administration to a marine salmon, indicating that TMA-mono-oxygenase is present in salmon liver.(ABSTRACT TRUNCATED AT 400 WORDS)

The relative importance of N-oxidation and N-demethylation in the metabolism of trimethylamine in man

1. 1. The metabolism of orally administered trimethylamine has been studied in 4 male volunteers at 2 dose levels. 2. 2. N-Oxidation was the major route of metabolism whilst N-demethylation was negligible and only significant at the higher dose level.

Metabolism of Trimethylamine, Choline, and Glycine Betaine by Sulfate-Reducing and Methanogenic Bacteria in Marine Sediments

The response of methanogenesis and sulfate reduction to trimethylamine, choline, and glycine betaine was examined in surface sediments from the intertidal region of Lowes Cove, Maine. Addition of these substrates markedly stimulated methanogenesis in the presence of active sulfate reduction, whereas addition of other substrates, including glucose, acetate, and glycine, had no effect on methane production. Sulfate reduction was stimulated simultaneously with methanogenesis by the various quaternary amines and all other substrates examined. Incubation of exogenous trimethylamine, choline, or glycine betaine with either bromoethane sulfonic acid or sodium molybdate was used to establish pathways of degradation of the substrates. Methanogenesis dominated the metabolism of trimethylamine, although limited nonmethanogenic activity, perhaps by sulfate-reducing bacteria, was observed. Acetate was oxidized primarily by sulfate reducers. Both choline and glycine betaine were fermented stoichiometrically to acetate and trimethylamine; apparently, neither substrate could be utilized directly by methanogens or sulfate reducers, and the activities of fermenters, methanogens, and sulfate reducers were all required to effect complete mineralization. These observations support the hypothesis that the presence of quaternary amines can mediate the coexistence of sulfate reduction and methanogenesis in marine surface sediments; they also implicate methanogens in the nitrogen cycle of marine sediments containing quaternary amines.

Problems which limit the use of rapeseed meal as a protein source in poultry diets.

AbstractThe occurrence of a ‘fishy’ or ‘crabby’ taint in eggs and liver damage culminating in massive haemorrhage has greatly restricted the commercial utilisation of rapeseed meal as a relatively cheap protein supplement for laying hens in the UK. Recent work on these problems is reviewed. It has elucidated the cause of the taint and identified the rapeseed constituents that are involved. A genetic defect impedes the synthesis of trimethylamine oxidase in susceptible hens and goitrin and tannins inhibit the enzyme. This biochemical lesion severely impairs the metabolism of trimethylamine which is released from sinapine and other dietary sources of choline by enteric bacteria. Consequently, excessive amounts pass into the yolk and produce the taint. Liver haemorrhage is associated with hepatocyte degeneration, abnormalities in the biliary system and the leakage of cellular enzymes into the plasma. The toxic substance(s) responsible has (have) not yet been identified.

Effect of rapeseed meal on trimethylamine metabolism in the domestic fowl in relation to egg taint

AbstractShaver 585 hens were classified as ‘tainters’ or ‘non‐tainters’ according to the trimethylamine (TMA) content of their eggs when they were fed a diet containing 10% rapeseed meal (from B. napus). They were then fed this diet or an equivalent soya‐bean diet for 5 to 8 weeks. Their ability to oxidise TMA was investigated by injecting 500 nmol of 14C‐TMA kg−1 intravenously and measuring the plasma levels of 14C‐trimethylamine oxide (TMA.O). The ‘tainters’ on the rapeseed diet gave a low flat curve (<0.1 nmol 14C‐trimethylamine oxide (TMA.O) ml−1) while the ‘nontainters’ gave a much higher curve with a peak (0.47 nmol ml−1) at 20 min. Higher peaks (0.6‐0.7 nmol ml−1) were given by the control groups. The ‘tainters’ on the rapeseed diet also had lower plasma 14C‐TMA levels for the first 45 min and excreted more radioactivity in the droppings, suggesting the involvement of another pathway of TMA metabolism.An experiment with Rhode Island Red x Light Sussex fowls confirmed the pronounced sensitivity of ‘tainters’ to the depression of TMA oxidation by rapeseed meal and showed that their low plasma 14C‐TMA.O levels were associated with low hepatic TMA oxidase activities (< 1 nmol TMA.O nig−1 protein 30 min−1). Two out of ten adult cocks were similarly affected and therefore were analogous to ‘tainters’. It was concluded that the 14 C‐TMA test could be utilised for trials to breed out the tainting characteristic from commercial flocks.

Effects of rapeseed meal on laying hens (Gallus domesticus) in relation to fatty liver-haemorrhagic syndrome and egg taint

Fatty liver-haemorrhagic syndrome (FLHS) occurred in the controls and was modified in hens that received a diet containing 10 per cent rapeseed meal. This diet increased the extent and severity of the hepatic haemorrhage without affecting the reticulin content of the liver but decreased the body weight and liver lipid levels and so weakened the correlation between these parameters and haemorrhage score found in FLHS. Plasma aspartate transaminase and beta-glucuronidase activities tended to increase with the score. The rapeseed meal diet also produced thyroid hypertrophy and since this was greater in the hens that produced tainted eggs and was positively correlated with the trimethylamine (TMA) content of the eggs it was postulated that rapeseed meal goitrogens may be involved as secondary factors in producing the disturbance in TMA metabolism that causes the egg taint. This abnormality was associated with a reduction in the soluble protein content of the liver, which reflected a decrease in TMA oxidase activity, but was not related to hepatic haemorrhage, steatosis or reticulolysis, or to lipid levels and the activities of lysosomal enzymes and transaminases in the plasma.

Aerobic and Anaerobic Metabolism of Trimethylamine, Dimethylamine and Methylamine in Hyphomicrobium X

Hyphomicrobium strain x was grown on trimethylamine and dimethylamine as the sole sources of carbon and energy under both aerobic and anaerobic conditions and the enzymes involved in the metabolism of these compounds were investigated. During aerobic growth of the organism on trimethylamine, accumulation and subsequent utilization of dimethylamine was observed. When the organism was grown on trimethylamine under anaerobic conditions in the presence of nitrate, a sequential accumulation and utilization of dimethylamine and methylamine was found. In cell-free extracts of Hyphomicrobium x grown on trimethylamine or dimethylamine under both aerobic and anaerobic conditions the following enzyme activities were detected: trimethylamine dehydrogenase, dimethylamine dehydrogenase, γ-glutamylmethylamide synthetase, N-methylglutamate dehydrogenase, methanol dehydrogenase, formaldehyde dehydrogenase, formate dehydrogenase and hydroxypyruvate reductase. Under neither growth condition were any of the following enzyme activities detected: trimethylamine mono-oxygenase, dimethylamine mono-oxygenase, trimethylamine-N-oxide aldolase (demethylase) and primary-amine dehydrogenase. Trimethylamine dehydrogenase and dimethylamine dehydrogenase were partially purified from bacteria grown on dimethylamine and the results suggest that in Hyphomicrobium x a novel enzyme, namely dimethylamine dehydrogenase, participates in the oxidation of dimethylamine.

Trimethylaminuria: the use of choline as an aid to diagnosis.

Trimethylamine metabolism can be studied by means of choline loading. The value and some limitations of the method are illustrated by results obtained in normal subjects, a patient with the Fish Odour syndrome and his kindred.

Trimethylamine metabolism in obligate and facultative methylotrophs.

1. Twelve bacterial isolates that grow with trimethylamine as sole source of carbon and energy were obtained in pure culture. All the isolates grow on methylamine, dimethylamine and trimethylamine. One isolate, bacterium 4B6, grows only on these methylamines whereas another isolate, bacterium C2A1, also grows on methanol but neither grows on methane; these two organisms are obligate methylotrophs. The other ten isolates grow on a variety of C(i) and other organic compounds and are therefore facultative methylotrophs. 2. Washed suspensions of the obligate methylotrophs bacteria 4B6 and C2A1, and of the facultative methylotrophs bacterium 5B1 and Pseudomonas 3A2, all grown on trimethylamine, oxidize trimethylamine, dimethylamine, formaldehyde and formate; only bacterium 5B1 and Ps. 3A2 oxidize trimethylamine N-oxide; only bacterium 4B6 does not oxidize methylamine. 3. Cell-free extracts of trimethylamine-grown bacteria 4B6 and C2A1 contain a trimethylamine dehydrogenase that requires phenazine methosulphate as primary hydrogen acceptor, and evidence is presented that this enzyme is important for the growth of bacterium 4B6 on trimethylamine. 4. Cell-free extracts of eight facultative methylotrophs, including bacterium 5B1 and Ps. 3A2, do not contain trimethylamine dehydrogenase but contain instead a trimethylamine monooxygenase and trimethylamine N-oxide demethylase. It is concluded that two different pathways for the oxidation of trimethylamine occur amongst the isolates.

The metabolism of trimethylamine N-oxide by Bacillus PM6.

Research Article| January 01 1971 The metabolism of trimethylamine N-oxide by Bacillus PM6 P A Myers; P A Myers Search for other works by this author on: This Site PubMed Google Scholar L J Zatman L J Zatman Search for other works by this author on: This Site PubMed Google Scholar Biochem J (1971) 121 (1): 10P. https://doi.org/10.1042/bj1210010Pa Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Cite Icon Cite Get Permissions Citation P A Myers, L J Zatman; The metabolism of trimethylamine N-oxide by Bacillus PM6. Biochem J 1 January 1971; 121 (1): 10P. doi: https://doi.org/10.1042/bj1210010Pa Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentAll JournalsBiochemical Journal Search Advanced Search This content is only available as a PDF. © 1971 The Biochemical Society1971 Article PDF first page preview Close Modal You do not currently have access to this content.