KINETIC-STUDIES ON THE GLUTAMATE-GLYOXYLATE TRANSAMINASE OF EUGLENA-GRACILIS

The kinetic properties of L-glutamate:glyoxylate transminase have been investigated. Glycine formation was linear with both protein concentr ation and incubation time. L-glutamate was the most effective amino do nor. Optimal concentrations for L-glutamate and glyoxylate were 150-20 0 mM and 10-20 mM, respectively. Initial velocity studies suggested a ping-pong reaction mechanism with a K-m value of 89.90-66.50 mM for L- glutamate and of 12.50-10.75 mM for glyoxylate. A competitive paraboli c substrate inhibition by glyoxylate at concentrations greater than 20 mM was observed. A pure linear non-competitive inhibition between gly oxylate and 4,5-dioxovaleric acid (1.1-2.8 mM) was found. We show here that in vivo different enzymes exist for the transamination of glyoxy late and DOVA.