The influence of linoleic acid intake on electron transport system components

Groups of young rats were fed a basal diet with beef tallow (BT) or corn oil (CO) added to provide 4 or 19% energy as linoleic acid. Mitochondria isolated from the livers of the rats fed the CO contained a significantly lower concentration of b‐type cytochrome and significantly higher concentrations of cytochromes c, c 1 and aa 3 . Cytochrome c oxidase activity also was elevated. The spectral characteristics of the b‐type cytochrome varied between the 2 groups. The mitochondria from the rats fed CO contained relatively more of the cytochrome b‐558 component whereas mitochondria from the BT group contained more of the cytochrome b‐562 component. The classical antimycin A inhibition of electron transport between cytochromes b and c 1 was partially bypassed in mitochondria with the more fluid membrane. The activation energy for cytochrome c oxidase in mitochondria from this group was significantly higher. These differences may be traced to the physical characteristics of the inner mitochondrial membrane.