The effect of complete substitution of D for H in succinic acid dehydrogenase on its enzymic activity

College of Physicians and Surgeons, Columbia University, New York City., U.S.A..

Abstract

A completely deuteriated enzyme, succinic dehydrogenase, has been prepared by growing E. coli in medium containing 99,5 atom % excess deuterium. Kinetic studies have been carried out using normal and deuterio-enzyme and substrate. The isotope effect noted when normal enzyme acts on deuteriosuceinate is abolished when heavy enzyme acts on deuteriosuecinate. Maionate inhibition studies of the enzyme suggest structural changes are responsible. The implications of these findings are discussed.