Reversible Inactivation of Dehydrogenases

Abstract 1. The reversible dissociation of lactic and malic dehydrogenases has been studied in detail and compared with the dissociation properties of triosephosphate dehydrogenase, α-glycerophosphate dehydrogenase, and liver alcohol dehydrogenase. 2. Evidence is presented for the existence of an intermediate form of lactic dehydrogenase with catalytic properties altered during reactivation. 3. The technique of reversible dissociation has been used to prepare interspecies hybrids of lactic, malic, and triosephosphate dehydrogenases. 4. Some of the catalytic and immunological properties of hybrid malic dehydrogenases have been examined. 5. The effects of salts on the reactivation of malic dehydrogenases have been investigated and related to previous results on lactic dehydrogenases. It is proposed that the observed salt effects may result from changes in the activity coefficients of the exposed peptide and amide groups.