Kinetics of chicken liver mitochondrial and cytoplasmic glutamate oxalacetate transaminase

Abstract

Electrophoresis at pH 7.4, on cellulose polyacetate strips, and specific staining, show the occurrence of two molecular forms of the mitochondrial and soluble isoenzymes from chicken liver aspartate aminotransferase. The optimum pH of the cytoplasmic enzyme with L-aspartate and alpha-ketoglutarate as substrats is approximately 7, while the mitochondrial one is practically unaffected in the interval 6-8. The kinetic reactional mechanism is of ping-pong bi-bi type for both enzymes, as confirmed by the method of Garces-Cleland, and their inhibitions by excess of the substrates L-aspartate and alpha-Ketoglutarate are competitive, in accordance with the proposed mechanism.