Ornithine delta-aminotransferase activity in retina and other tissues.
Ornithine delta-aminotransferase (OAT) activity was determined in liver, kidney, brain, retina and ciliary body-iris of rat, rabbit, calf and human. OAT activities (nanomoles delta 1-pyrroline-5-carboxylate/mg protein/hr) in retina were (mean +/- SE) 324 +/- 43, 240 +/- 24, 234 +/- 26 and 218 +/- 22 respectively in rat, rabbit, calf and human. The OAT activities in retina were three times higher than in brain and 80% of that of liver. 2-oxoglutarate was the preferred amino acceptor substrate for OAT activity. In rat retina the activities of OAT with glyoxalate, beta-hydroxypyruvate, pyruvate, and oxaloacetate were 51, 44, 30, and 30% of that of 2-oxoglutarate respectively. A lack of substrate OAT specificity indicates OAT deficiency such as occur in gyrate atrophy of the choroid and retina could impair metabolism of ketoacids. A candidate for possible toxicity to the retina in OAT deficiency is glyoxalate. Arginine glycine transamidinase activity was not detectable in human retina, thus a previously postulated creatine phosphate deprivation in OAT deficiency may not be applicable to the pathogenesis of the disease.
D000818:Animals; D001921:Brain / Q000201:enzymology; D002417:Cattle; D002924:Ciliary Body / Q000201:enzymology; D006801:Humans; D007498:Iris / Q000201:enzymology; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D009953:Ornithine-Oxo-Acid Transaminase / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D012160:Retina / Q000201:enzymology*; D013045:Species Specificity; D014018:Tissue Distribution; D000637:Transaminases / Q000378:metabolism*
D000637:Transaminases; D009953:Ornithine-Oxo-Acid Transaminase