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 concentration and incubation time. L-glutamate was the most effective amino donor. Optimal concentrations for L-glutamate and glyoxylate were 150-200 mM and 10-20 mM, r...
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| Autores principales: | , , |
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_10111344_v36_n3_p241_Lombardo |
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| Sumario: | The kinetic properties of L-glutamate:glyoxylate transminase have been investigated. Glycine formation was linear with both protein concentration and incubation time. L-glutamate was the most effective amino donor. Optimal concentrations for L-glutamate and glyoxylate were 150-200 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 parabolic substrate inhibition by glyoxylate at concentrations greater than 20 mM was observed. A pure linear non-competitive inhibition between glyoxylate 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 glyoxylate and DOVA. |
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