Delta 1-pyrroline-5-carboxylate dehydrogenase, a possible regulatory enzyme in transmitter glutamic acid metabolism--a preliminary report.

At 10 mM (unless stated), GABA (5 mM), glycine and hydroxyproline inhibited delta 1-pyrroline-5-carboxylate dehydrogenase by 84, 85 and 76%, respectively. Glutamate, glutamine, proline, cysteine and alanine inhibited delta 1-pyrroline-5-carboxylate dehydrogenase by 41-59%. Other amino acids studied were either ineffective or marginally effective. It is concluded that delta 1-pyrroline-5-carboxylate dehydrogenase may be a regulatory enzyme in the ornithine-glutamate pathway.