Ornithine-ketoacid transaminase was purified from rat liver mitochondria to an almost single protein on starch zone electrophoresis and ultracentrifugation pattern. The purified enzyme is 400-fold in the purity. Physico-chemical properties of the enzyme were studied and gave the following values; S20, w; 7.1 × 10−13M, optimum pH; 8.2, Km for α-ketoglutarate 8.45×10−4M, for ornithine; 6.0×10−4M. Substrate specificity of the enzyme with respect to ketoacid was studied and the following reaction rates were observed, α-Ketoglutarate 100, glyoxalate 19, pyruvate 3 and oxaloacetate 0.7. The enzyme was found to require pyridoxal phosphate as the coenzyme. Canalline strongly inhibited the enzyme reaction. Oxaloacetate inhibited the reaction competitively with α-ketoglutarate. L-Valine, L-isoleucine and L-leucine were also found to be the inhibitors of the enzyme.
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Katunuma et al. (1964) studied this question.