Studies on isocitrate oxidation in mitochondria of normal rat liver and azo-dye-induced hepatomas

Abstract

Mitochondria of rat-liver hepatomas induced by feeding with 4-dimethylamino-3[image]-methylazobenzene and 4-dimethylaminoazobenzene possess both NAD- and NADP-linked isocitrate-dehydrogenase systems. In contrast with the results obtained on the NAD-linked isocitrate-dehydrogenase system of normal rat-liver mitochondria, activity, associated with this enzyme system in the tumor mitochondria could be demonstrated at the dehydrogenase level or with 2,6-dichlorophenol-indophenol as electron acceptor. Mitochondria of the 4-dimethylamino-3[image]-methylazooenzene-induced tumor stored for 168 hr. at 0[degree] lose 47% of their NAD-linked isocitrate-diaphorase activity, whereas NADP-diaphorase activity is enhanced by 47%.