Enzymes metabolizing delta1-pyrroline-5-carboxylate in rat tissues.
The direction and capacity for the metabolism of delta1-pyrroline-5-carboxylate in a number of rat tissues ere investigated by measuring the activities of delta1-pyrroline-5-carboxylate reductase, delta1-pyrroline-5-carboxylate dehydrogenase and proline oxidase. Each of these enzymes catalyzed unidirectional reactions in which delta1-pyrroline-5-carboxylate was either the substrate or product. Delta1-Pyrroline-5-carboxylate reductase activities that were much higher than any previously reported were obtained by avoiding its inactivation in the cold. delta1-Pyrroline-5-carboxylate dehydrogenase, previously said to act on both D- and L-isomers of delta1-pyrroline-5-carboxylate, acted only on the L-isomer. Proline oxidase could not be measured in two adult tissues, in which an inhibitor appeared after birth. The activity of delta1-pyrroline-5-carboxylate reductase significantly paralleled that of ornithine aminotransferase in 23 tissues, showing a widespread potential for proline synthesis from ornithine. An independently distributed potential in fewer tissues for proline degradation to alpha-oxoglutarate was shown by the significantly similar tissue distributions of proline oxidase. Delta1-pyrroline-5-carboxylate dehydrogenase and glutamate dehydrogenase. Reverse metabolism of glutamate or proline to ornithine would be atypical in rat tissues with these distributions of unidirectional enzyme reactions.
D000818:Animals; D005333:Fetus / Q000201:enzymology; D009374:Neoplasms, Experimental / Q000201:enzymology; D010088:Oxidoreductases / Q000378:metabolism; D011392:Proline; D011758:Pyrroles / Q000378:metabolism*; D011762:Pyrroline Carboxylate Reductases / Q000378:metabolism; D051381:Rats; D013237:Stereoisomerism; D013696:Temperature
D011758:Pyrroles; C015485:delta-1-pyrroline-5-carboxylate; D011392:Proline; D010088:Oxidoreductases; D011762:Pyrroline Carboxylate Reductases