Glutamate transaminase

Branched-chain amino acid glutamate transaminase... 

Arginine Proline Proline oxidase Ornithine-glutamate transaminase Ornithine transcarbamoylase Argininosuccinate synthase Argininosuccinate lyase... 

Glycolytic flux through the Embden— Myerhof pathway is obviously decreased in hypoglycaemia, contributing to a decreased cerebral metabolic rate for glucose (CMRgl) (Abdul-Rahman and Siesjo, 1980). Transamination reactions occur, and the aspartate—glutamate transaminase reaction is shifted to the left (Fig. 3.1). 

Fig. 3.1 Altered metabolism of excitatory amino acids during hypoglycemic coma. Oxaloacetate and a-ketoglutarate are the corresponding a-keto-acids to aspartate and glutamate, respectively. During hypoglycemia the aspartate—glutamate transaminase reaction is driven to the left...

Transaminases serve two vital roles. First, they provide a means of adjusting the relative proportions of amino acids to meet the particular needs of an organism. Second, they collect the nitrogen atoms of all amino acids into glutamate, because glutamate is the central source of nitrogen atoms for biosynthesis. An example of the reaction catalyzed by glutamate transaminase is presented here. 

The oxidation of L-aspartate (but not of the D-isomer) was accomplished by Nakada and Weinhouse" with washed homogenates of rat liver, upon the addition of either AMP or ATP. The interpretation of the authors is that the oxidation of L-aspartate is not due to a specific oxidase, but that it is caused by the transamination of the amino acid to oxal-acetate, which is subsequently oxidized through the operation of the citric acid cycle. The occurrence of aspartic-glutamic transaminase was demonstrated by assay and by the accumulation of glutamic acid. 

I, pyruvate kinase 2, OS17 enzyme 3, 3-hydroxypropionyl-CoA dehydratase 4, lactate dehydrogenase 5, CoA transferase 6, 3-hyd roxy propiony l-CoA/3-hyd roxy i sobutryl-CoA hydrolase 7, lactyl-CoA dehydratase 8, pyruvate/glutamate transaminase 9, alanine dehydrogenase 10, alanine 2,3-aminomutase ... 

M. Recasenses, M.M. Gabellec, G. lack and P. Mandel. Comnara-tive study of miscellaneous properties of cysteinesulfinate transaminase and glutamate transaminase in chick retina homogenate. Neurochemical Res., 1978, 3 27. 

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