TABLE 2
Concentrations and activities of cytochrome b5, NADH cytochrome b5 reductase, and cytochrome P450 in investigated mitochondria of various organs and species
Enzyme activities were measured spectrophotometrically. Cytochrome b5 was estimated from difference spectra between the oxidized and NADH-reduced preparation (Estabrook and Werringloer, 1978). To determine the cytochrome b5 content in pig kidney mitochondria, the protein suspension was sonicated before measuring difference spectra. NADH cytochrome b5 reductase was determined by a modification of the ferricyanide reduction assay (Mihara and Sato, 1978). Cytochrome P450 was determined by carbon monoxide difference spectra after preincubation of the enzyme preparation with 0.05% Triton X-100 (Omura and Sato, 1964).