Coenzyme A transferase active site Coenzyme A (CoA) transferases belong to an evolutionary conserved [<cite idref="PUB00002192"/>, <cite idref="PUB00002998"/>] family of enzymes catalyzing the reversible transfer of CoA from one carboxylic acid to another. They have been identified in many prokaryotes and in mammalian tissues. The bacterial enzymes are heterodimers of two subunits (A and B) of about 25 Kd each while eukaryotic SCOT consists of a single chain which is colinear with the two bacterial subunits. This signature corresponds to a region in the N terminus of the B subunit which contains a glutamate that is involved in the catalytic mechanism.