The L‐form of N‐7‐mercaptoheptanoyl‐O‐phosphothreonine is the enantiomer active as component B in methyl‐CoM reduction to methane

Abstract The reduction of methyl-CoM to methane in methanogenic bacteria is dependent on a low- M r , heat-stable compound designated component B, the structure of which has recently been assigned as N -7-mercaptoheptanoyl- O -phosphothreonine. We report here that only the enantiomer derived from O -phospho-L-threonine has cofactor activity. N -7-Mercaptoheptanoyl- O -phospho-D-threonine was neither active nor inhibitory.