Nutritional aspect of methionine isomers studied by pulmonary exhalation of dimethyl sulfide and urinary excretion of .ALPHA.-keto-.GAMMA.-methiolbutyrate in humans.

Abstract

With the view of evaluating the relative utilization of methionine isomers, the pulmonary exhalation of dimethyl sulfide and methyl mercaptan and the urinary excretion of a-keto-7-methiolbutyrate were studied in normal healthy subjects following oral or intravenous administration of L-or D-isomerof methionine. Dimethyl sulfide concentration in the expired alveolar gas (mean ± SD) before methionine loading was 2.1 ± 1.4 ng/dl (N=23). Maximumconcentrations of dimethyl sulfide in oral methionine loading tests were: 56.0 ± 24.9 ng/dl (D-2g) (n=4), 66.0 ± 42.1 (D-lg) (N=6) and 4.6 ± 2.6 (L-2g) (N=4);and in intravenous loading tests: 60.0 ± 19.9 (D-lg) (N=4) and 4.2 ± 2.1 (L-2g) (N=3), respectively. The changes in methyl mercaptan in the expired alveolar gas were small and were disproportional to the changes in dimethyl sulfide following administration of both isomers. Preloading concentration of a-keto-7-methiolbutyrate in urine was 0.15 ± 0.10 Mg/mg Creatinine (mean ± SD) (N=5). Postloading values during the initial two hours were 578 and 156 Mg/mg Creatinine following 3g of D-and 0.20 and 29.7 Mg/mg Creatinine following 3g of L-methionine ingestion, In view of the results obtained, significant amounts of D-methionine seem to be metabolized through the transaminative pathway of methionine metabolism.

Metabolic Fingerprint of Dimethyl Sulfone (DMSO2) in Microbial–Mammalian Co-metabolism

“…The production of DMS is relatively small after administration of 3 g of L-methionine. 162 DMS increased prominently in normal subjects following both oral and parenteral administration of D-methionine, suggesting this route of metabolism might be independent of intestinal microbial activity. 166 Interestingly, MAT I/III deficient patients who have abnormal methionine production exhibit a significantly higher DMSO 2 level in plasma compared to controls.…”

“…Exhaled DMS increased markedly in normal subjects after intravenous injection of 2 g d -methionine, but not after 500 mg of d -methionine, nor 2 g of l -methionine. The production of DMS is relatively small after administration of 3 g of l -methionine . DMS increased prominently in normal subjects following both oral and parenteral administration of d -methionine, suggesting this route of metabolism might be independent of intestinal microbial activity .…”

“…This catabolic pathway requires a high methionine concentration and does not likely occur under normal circumstances (reviewed in refs − ). l -Methionine toxicity and elevated transamination have been found in healthy subjects after oral administration of 0.1 g l -methionine per kg body weight, but more intensively seen in methionine adenosyltransferase (MAT) deficient patients and induced by d -methionine administration …”

Dimethylsulphidemia: the significance of dimethyl sulphide in extra-oral, blood borne halitosis

“…Since DMSE accompanies HME, breath DMS can be used to screen for HME. [135][136][137] A breath DMS level of 96 nM was reported in a patient with isolated persistent hypermethioninaemia secondary to MAT deficiency. 122 Since DMSE can be caused by other conditions, elevated breath DMS is not specific for HME.…”

Wool and Reduced Sulphur Gases in Museum Air

“…Sulphides are found in both expired air [25,26] and flatus, although in the latter case the trace sulphide composition is poorly known [27]. The comparatively low contribution made by clothing is apparent when we consider the amount of human bioeffluents released within a gallery.…”