Octopine déshydrogénase Purification et propriétés catalytiques

Abstract

Octopine dehydrogenase: Purification and catalytic properties 1. I. Octopine dehydrogenase, an NAD + enzyme, which catalyzes the dehydrogenation of octopine into arginine plus pyruvale, has been purified from muscles of Pecten maximus. It is homogeneous on analytical ultracentrifugation and disc electrophoresis. 2. 2. The enzyme contains no such metal cofactor as Fe 2+, Mn 2+, Zn 2+. 3. 3. The Michaelis constants are: 1.5·10 −3 M for octopine, arginine and pyruvate, 1.5·10 −4 M for NAD + and 4·10 −5 M for NADH. 4. 4. Substrate analogs with a guanidyl (guanidinobutane) or a carboxyl group (valeric acid) or both of them (δ-guanidinovaleric acid) are competitive inhibitors of the octopine forming reaction. In the dehydrogenation reaction, compounds with only one of these groups are competitive inhibitors whereas those possessing both guanidyl and carboxyl groups are not.