Two human subjects were given separate oral doses of sodium [2H6]isobutyrate and [methyl-2H3]thymine and the labelling patterns of urinary metabolites were determined. Ingestion of deuterated isobutyrate resulted in the excretion of 2H5-labelled S-3-hydroxyisobutyric acid, formed on the direct catabolic pathway, and of S- and R-[2H4]-3-hydroxyisobutyric acids, formed by the reduction of S- and R-methylmalonic semialdehydes respectively. Only the R-enantiomer of urinary 3-hydroxyisobutyric acid was labelled by thymine. This labelling pattern indicates a flow from S- to R-methylmalonic semialdehyde, suggesting that the R-enantiomer is the substrate of methylmalonic semialdehyde dehydrogenase.
Research Article|October 15 1985
Tracer studies of the interconversion of R- and S-methylmalonic semialdehydes in man
Biochem J (1985) 231 (2): 481-484.
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N J Manning, R J Pollitt; Tracer studies of the interconversion of R- and S-methylmalonic semialdehydes in man. Biochem J 15 October 1985; 231 (2): 481–484. doi: https://doi.org/10.1042/bj2310481
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