Alcohol dehydrogenase deuterium isotope effect

Once intrinsic isotope effects are determined, one is in a position to deduce transition state stmcture, just as the physical organic chemist does for nonen-zymic reactions. Unfortunately, in many cases workers have assumed, rather than proved, that commitments are zero and intrinsic isotope effects were being looked at. Transition state structures have been investigated in the formate and liver alcohol dehydrogenase reactions as the redox potential of the nucleotide substrate was changed (103, 118). Primary deuterium and C, secondary deuterium, and for formate dehydrogenase 0 isotope effects were determined. In both cases the transition states appeared to be late with NAD and to become earlier as the redox potential of the nucleotide became more positive. So far the conclusions from such studies have been qualitative in nature, and there is room for much more work on these systems. 

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