Discovery of sarcosine dimethylglycine methyltransferase from Galdieria sulphuraria

An enzyme with sarcosine dimethylglycine methyltransferase (SDMT) activity has been identified in the thermophilic eukaryote, Galdieria sulphuraria . The crystal structure of the enzyme, solved to a resolution of 1.95 Å, revealed a fold highly similar to that of mycolic acid synthases. The k cat and apparent K M values were 64.3 min −1 and 2.0 m M for sarcosine and 85.6 min −1 and 2.8 mM for dimethylglycine, respectively. Apparent K M values of S‐adenosylmethionine were 144 and 150 μ M for sarcosine and dimethylglycine, respectively, and the enzyme melting temperature was 61.1°C. Modeling of cofactor binding in the active site based on the structure of methoxy mycolic acid synthase 2 revealed a number of conserved interactions within the active site. Proteins 2009. © 2008 Wiley‐Liss, Inc.