Open AccessMICRODETERMINATION OF CYTOCHROME OXIDASE IN RAT TISSUES BY THE OXIDATION OF N-PHENYL-p-PHENYLENEDIAMINE OR ASCORBIC ACID
Author(s) -
William Pearl,
Joseph Cascarano,
Benjamin W. Zweifach
Publication year - 1963
Publication title -
journal of histochemistry and cytochemistry/the journal of histochemistry and cytochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.971
H-Index - 124
eISSN - 1551-5044
pISSN - 0022-1554
DOI - 10.1177/11.1.102
Subject(s) - ascorbic acid , chemistry , cytochrome c oxidase , cytochrome , biochemistry , oxidase test , enzyme , substrate (aquarium) , cytochrome c , nuclear chemistry , mitochondrion , food science , biology , ecology
The cytochrome oxidase content of rat tissues was investigated, utilizing the accumulation of the free radical formed by the emzymatic, univalent oxidation of a stable, non-toxic substrate, N-phenyl- p-phenylenediamine ( p-aminodiphenylamine). This procedure eliminated the non-enzymatic coupling of the radical with α-naphthol, found in the classic Nadi reaction. Using homogenates, the following decreasing order of enzyme activity was found: heart, kidney, diaphragm, liver, rectus abdominis. A more sensitive assay was also developed, involving the reduction of cytochrome c by ascorbic acid, and using 2-( p-iodophenyl)-3-( p-nitrophenyl)-5-phenyl tetrazolium chloride to analyze unoxidized ascorbic acid. The same order of tissue activity was demonstrated. The cytochrome oxidase content of a tissue may be a reflection of its physiological role.