CYTOCHROME-OXIDASE ACTIVITY OF INDIVIDUAL MITOCHONDRION AS QUANTIFIEDBY PLATINUM-DIAMINOBENZIDINE REACTION WITH ENERGY-DISPERSIVE X-RAY ANALYZER

The platinum diaminobenzidine (Pt-DAB) reaction was characterized by t he oxidative polymerization of DAB with a concurrent incorporation of Pt atoms into the polymerization product in the presence of cytochrome oxidase activity. It conformed to the Michaelis-Menten's formula show ing its enzymatic nature. It was specific to the oxidase as proved by the suppressive effects due to some inhibitors and heat. It permitted the quantification of the oxidase activity of an individual mitochondr ion and its constituent part by energy dispersive X-ray analysis (EDAX ) owing to the incorporated Pt atoms, To elucidate the gradient in the oxidase activity along the radial axis of a liver lobule, the local a ctivity difference between the hepatocytes in the peripheral region (P E) adjacent to the triad and those in the central region (CN) close to the central vein was quantified at individual mitochondrial level. Th e mitochondria in the PE hepatocytes were found 1.5 times stronger in activity per area of the reactive site than those in the CN hepatocyte s.