Prominent glutamine oxidation activity in mitochondria of avian transplantable hepatoma induced by MC-29 virus.
Well coupled mitochondria were isolated from transplantable chicken hepatoma induced by MC-29 virus. The mitochondrial phosphate-dependent and phosphate-independent glutaminase activities were increased compared with those from normal chicken liver. Glutamate dehydrogenase was undetectable in the tumor mitochondria. Oxypolarographic tests showed the following: glutamine oxidation was prominent in the tumor mitochondria and was mediated through an NAD-linked reaction, while mitochondria from the liver showed a feeble glutamine oxidation; glutamine oxidation by tumor mitochondria was inhibited either by aminooxyacetate, inhibitor of transaminases, or prior incubation of mitochondria with DON (6-diazo-5-oxonorleucine), which inhibited mitochondrial glutaminases. Bromofuroate, inhibitor of glutamate dehydrogenase, had little or no effect; and glutamate oxidation was also inhibited by aminooxyacetate, while it was not affected by DON. These findings clearly show a high glutamate oxidation activity in the hepatoma and indicate that the product of glutamine hydrolysis, glutamate, is catabolized via transamination in the mitochondria to supply ATP.
D000818:Animals; D001354:Avian Leukosis Virus; D002645:Chickens; D005969:Glutamate Dehydrogenase / Q000172:deficiency / Q000378:metabolism; D005972:Glutaminase / Q000037:antagonists & inhibitors / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism*; D008114:Liver Neoplasms, Experimental / Q000201:enzymology / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000201:enzymology / Q000378:metabolism*; D010101:Oxygen Consumption; D000637:Transaminases / Q000378:metabolism
D005973:Glutamine; D005969:Glutamate Dehydrogenase; D000637:Transaminases; C020656:glutamine-pyruvate aminotransferase; D005972:Glutaminase