Glutamate-glyoxylate aminotransferase

Lawyer, A.L. and I. Zelitch Inhibition of glutamate Glyoxylate aminotransferase activity in tobacco leaves and callus by glycidate, an inhibitor of photorespiration Plant Physiol. 61 (1978) 242-247. 

Aminopeptidase, cytosol Aminopeptidase, leucine Aminopropyltransferase, putrescine Aminotransferase Aminotransferase, alanine Aminotransferase, aspartate Aminotransferase, glutamate-glyoxylate Aminotransferase, ornithine-keto acid Aminotransferase, serine-glyoxylate Ammonia... 

The isolation of the six clearly defined and well-characterized classes of mutant plants deficient in the enzymes shown in Table I emphatically demonstrates the role of nitrogen metabolism in the process of photorespiration and photosynthesis. It is unfortunate that the one provisionally identified mutant of barley lacking glutamate glyoxylate aminotransferase has since died. 

This enzyme [EC 2.6.1.2], also known as glutamic-pyruvic transaminase and glutamic-alanine transaminase, catalyzes the pyridoxal-phosphate-dependent reaction of alanine with 2-ketoglutarate, resulting on the production of pyruvate and glutamate. 2-Aminobutanoate will also react, albeit slowly. There is another alanine aminotransferase [EC 2.6.1.12], better known as alanine-oxo-acid aminotransferase, which catalyzes the pyridoxal-phosphate-dependent reaction of alanine and a 2-keto acid to generate pyruvate and an amino acid. See also Alanine Glyoxylate Aminotransferase... 

This pyridoxal-phosphate-dependent enzyme [EC 2.6.1.4] catalyzes the reaction of glycine with a-ketoglu-tarate (or, 2-oxoglutarate) to produce glyoxylate and l-glutamate. See also GlycineiOxaloacetate Aminotransferase Glyoxylate Aminotransferase A. E. Braunstein (1973) The Enzymes, 3rd ed., 9, 379. 

The enzymes utilizing serine as amino donor and glyoxylate as amino acceptor are considered together here. Much attention has been paid to these aminotransferases, with the role of these enzymes in photorespiration being a particular focus of interest (see Keys, this volume. Chapter 9). Initial studies on impure extracts indicated the presence of glyoxylate aminotransferases which could use glutamate, aspartate, alanine, and serine as amino donors. The best donor to glyoxylate varied from one tissue to another (Cossins and Sinha, 1965). Leaf peroxisomes were subsequently shown to... 

Fig. 1. Main routes involved in the synthesis and interconversion of glycine and serine in plants. The various steps are numbered, and the necessary enzymes are as follows 1, glycolate oxidase, E.C. 1.1.3.1 2, aminotransferases, serine, E.C. 2.6.1.45, and glutamate, E.C. 2.6.1.4, glyoxylate aminotransferases 3, enzyme complex in mitochondria (see Fig. 2) 4, serine-glyoxylate aminotransferase, E.C. 2.6.1.45 5, glycerate dehydrogenase, E.C. 1.1.1.29 6, glycerate kinase E.C. 2.7.1.31 7, D-3-phosphoglycerate phosphatase, E.C. 3.1.3.38 8, d-3-phosphoglycerate dehydrogenase, E.C. 1.1.1.95 9, phosphoserine aminotransferase, E.C. 2.6.1.52 10, phosphoserine phosphatase, E.C. 3.1.3.3 11, serine hydroxymethyltransferase E.C. 2.1.2.1 12, nonenzymatic decarboxylation 13, formyl tetrahydrofolate synthetase, E.C. 6.3.4.3 14, isocitrate iyase, E.C. 4.1.3.1.

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