[NAD(NADP)-dependent glyceraldehyde 3-phosphate dehydrogenase from Chlorella. Kinetics of inhibition by the reaction products NAD and NADP].

The values of Km and V for NAD(NADP)-dependent glyceraldehyde 3-phosphate dehydrogenase from Chlorella for oxidized and reduced pyridine nucleotides were determined. NAD and NADP competitively inhibit the oxidation of NADH and NADPH, respectively. The NADPH- and NADH-dependent activities were shown to be "cross"-inhibited by NAD and NADP, the inhibition being of a mixed type. It is concluded that the enzyme has independent sites for binding of coenzymes NAD(H) and NADP(H) or at least these coenzymes are linked by different ways at the same site of the enzyme molecule.