Pulse fluorimetry study of octopine dehydrogenase-reduced nicotinamide adenine dinucleotide complexes.

We measured the transient fluorescence of NADH bound to octopine dehydrogenase in the binary octopine dehydrogenase-NADH complex and in the ternary complexes containing D-octopine, L-allooctopine, L-arginine, D-arginine, or 5-guanidinovaleric acid. The fluorescence decay in all these complexes is biexponential. This is explained by the presence of several conformations of the single NADH binding site. In addition, transietn anisotropy measurements show that the nicotinamide moiety is rigidly bound to the enzyme.