Characterization of glycine sarcosine N-methyltransferase and sarcosine dimethylglycine N-methyltransferase

Antti Nyyssölä (Corresponding Author), Tapani Reinikainen, Matti Leisola

    Research output: Contribution to journalArticlepeer-review

    32 Citations (Scopus)

    Abstract

    Glycine betaine is accumulated in cells living in high salt concentrations to balance the osmotic pressure. Glycine sarcosine N-methyltransferase (GSMT) and sarcosine dimethylglycine N-methyltransferase (SDMT) of Ectothiorhodospira halochloris catalyze the threefold methylation of glycine to betaine, with S-adenosylmethionine acting as the methyl group donor. These methyltransferases were expressed in Escherichia coli and purified, and some of their enzymatic properties were characterized. Both enzymes had high substrate specificities and pH optima near the physiological pH. No evidence of cofactors was found. The enzymes showed Michaelis-Menten kinetics for their substrates. The apparent Km and Vmax values were determined for all substrates when the other substrate was present in saturating concentrations. Both enzymes were strongly inhibited by the reaction product S-adenosylhomocysteine. Betaine inhibited the methylation reactions only at high concentrations.
    Original languageEnglish
    Pages (from-to)2044-2050
    Number of pages7
    JournalApplied and Environmental Microbiology
    Volume67
    Issue number5
    DOIs
    Publication statusPublished - 2001
    MoE publication typeA1 Journal article-refereed

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