The stereospecificity of sequential nicotinamide-adenine dinucleotide-dependent oxidoreductases in relation to the evolution of metabolic sequences

摘要

pThe generalization that ‘when a metabolic sequence involves consecutive nicotinamide-adenine dinucleotide-dependent reactions, the dehydrogenases have the same stereospecificity’ was tested and confirmed for three metabolic sequences. (1) NADsup+/sup-xylitol (D-xylulose) dehydrogenase and NADPsup+/sup-xylitol (L-xylulose) dehydrogenase are both B-specific. (2) D-Mannitol 1-phosphate dehydrogenase and D-sorbitol 6-phosphate dehydrogenase are both B-specific. (3) imeso/i Tartrate dehydrogenase and oxaloglycollate reductive decarboxylase are both A-specific. Other dehydrogenases associated with the metabolism of meso-tartrate in iPseudomonas putida/i, such as hydroxypyruvate reductase and tartronate semialdehyde reductase, were also shown to be A-specific. Malate dehydrogenase from iPseudomonas putida/i was A-specific, and the proposition is discussed that the common A-stereospecificity among the dehydrogenases involved in meso-tartrate metabolism reflects their origin from malate dehydrogenase./p