Glycine/sarcosine/dimethylglycine N-methyltransferase

Glycine/sarcosine/dimethylglycine N-methyltransferase (, GSDMT, glycine sarcosine dimethylglycine N-methyltransferase) is an enzyme with systematic name S-adenosyl-L-methionine:glycine(or sarcosine or N,N-dimethylglycine) N-methyltransferase (sarcosine(or N,N-dimethylglycine or betaine)-forming). This enzyme catalyses the following chemical reaction

: 3 S-adenosyl-L-methionine + glycine \rightleftharpoons 3 S-adenosyl-L-homocysteine + betaine (overall reaction) :(1a) S-adenosyl-L-methionine + glycine \rightleftharpoons S-adenosyl-L-homocysteine + sarcosine :(1b) S-adenosyl-L-methionine + sarcosine \rightleftharpoons S-adenosyl-L-homocysteine + N,N-dimethylglycine :(1c) S-adenosyl-L-methionine + N,N-dimethylglycine \rightleftharpoons S-adenosyl-L-homocysteine + betaine

This enzyme from the halophilic methanoarchaeon Methanohalophilus portucalensis can methylate glycine and all of its intermediates to form the compatible solute trimethylglycine.