The mechanistic and evolutionary basis of stereospecificity for hydrogen transfers in enzyme-catalyzed processes

摘要

The origin of stereospecificity in enzyme-catalysed processes is attributed to either mechanistic imperatives or to the evolutionary origin of an enzyme, Recent analysis of the syn-anti dichotomy for hydratase-dehydratase enzymes has clearly demonstrated that it is a historical contingency that has played a significant role in determination of stereospecificity, Historical contingencies also appear to play a significant role in (a) the selection of one out of a possible eight different stereochemical courses available for an enoyl thioester reductase, and (b) the discrimination between diastereotopic hydrogens in coenzyme B-12-dependent rearrangements.