Glutamate Dehydrogenase and a Proposed Glutamate-Aspartate Pathway for Citrate Synthesis in Rat Ventral Prostate

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Abstract
Glutamate dehydrogenase activity was determined in mitochondrial preparations from rat ventral prostate and rat kidney. Kinetic parameters of the ventral prostate enzyme were comparable to those for the kidney enzyme. Glutamate dehydrogenase activity in the direction of glutamate oxidative deamination was inhibited by .alpha.-ketoglutarate. The characteristics of .alpha.-ketoglutarate inhibition indicated that glutamate oxidation via glutamate dehydrogenase can occur at in vivo prostatic .alpha.-ketoglutarate levels. Glutamate dehydrogenase activity in prostate may provide a continuous source of .alpha.-ketoglutarate for aspartate transamination to oxalacetate and ultimate citrate synthesis. In addition prostate mitochondria are able to couple the glutamic dehydrogenase reaction to asparate aminotransferase. Under these conditions aspartate in the presence of glutamate and acetyl-CoA will result in a net synthesis of citrate. An aspartate-glutamate pathway for citrate synthesis in the prostate is proposed.