Reversible denaturation of thermophilic malate dehydrogenase by guanidine hydrochloride and acid.

摘要: Thermophilic malate dehydrogenase [L-malate:NAD+ oxidoreductase, EC 1.1.1.37] was denatured at pH 2.0 with complete loss of enzyme activity but without dissociation to monomers, suggesting the presence strong intersubunit contact. On other hand, completely and dissociated monomers in 5 M GdnHCl. Inactivation denaturation by acid GdnHCl were reversible. Upon dilution denaturants, inactivated regained native structure high yield (80-90%). Kinetic analyses reactivation revealed that reaction obeyed first-order kinetics. The rate constant Arrhenius activation energy acid-inactivated almost same as those These results suggest rate-limiting steps processes are a conformational change inactive dimer active is step reaction.