Glutamate dehydrogenase location

The equilibrium for this reaction favors glutamate the reaction is driven by the consumption of ammonia. Glutamate dehydrogenase is located in mitochondria, as are some of the other enzymes required for the production of urea. This compartmentalization sequesters free ammonia, which is toxic. 

It is of interest that many of the key enzymes in urea synthesis are located in the mitochondria. The mitochondrial enzymes include several transaminases, especially glutamate-oxaloacetate transaminase, as well as glutamate dehydrogenase, carbamoyl phosphate synthase, ornithine transcarbamylase and A -acetylglutamate synthase. 

To test the latter possibility mitochondria were further fractionated with digitonin and the enzymes determined in intramitochondrial compartments. As shown in Pig,3 over 80% of the activity of all three sulphur-transferases was recovered in the matrix fraction, similarly to malate and glutamate dehydrogenases. There is no indication that the sulphurtransferases are located either in the intermembrane space or in the membranes, since their activities in these fractions are the same as those of the two marker enzymes for the matrix. 

P.J. Baker, K.L. Britton, PC. Engel, G.W. Farrants, K.S. Lilley, D.W. Rice, T.J. Stillman, Subunit assembly and active-site location in the structure of glutamate-dehydrogenase. Protein Struct. Fund Genet. 12 (1) (1992) 75-86. 

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