Abstract

The properties of ornithine aminotransferase, which catalyzes the transfer of S-NH2 group of ornithine to α-ketoacids were characterized in the post-mortem human tissues. The enzyme was distributed in all human tissues tested especially high in small intestine and its activity was increasing in liver and kidney but decreasing in small intestine with age. The intestinal enzyme being reactive with α-ketoglutarate, glyoxylate, pyruvate and oxaloacetate in decreasing order was very heat-unstable but its inactivation by heat-treatment was partially prevented by the presence of pyridoxal phosphate. The enzyme was completely inhibited by p-hydroxy-mercuritenzoate, suggesting that SH-group of enzyme protein is essential for catalytic action.