Distribution of selenium-dependent and nonselenium-dependent glutathione peroxidase activity in tissues of young cattle.

Separation by gel-filtration chromatography and enzyme assay with H2O2 and an organic hydroperoxide substrate were used to identify selenium (Se)-dependent and non-Se-dependent glutathione peroxidase (GSH-Px) in tissues of calves fed supplemented whole milk diets differing only in their Se content (0.03, 0.23, and 0.53 microgram/g of total solids). Spleen, cardiac muscle, erythrocytes, brain, thymus, adipose tissue, and striated muscles of calves were found to contain only the Se-dependent GSH-Px. Tissues having both enzymes included liver, lungs, adrenal glands, testes, kidney medulla, and kidney cortex. Hepatic tissue contained the highest percentage of non-Se-dependent GSH-Px activity of the calf tissues. For those tissues having Se-dependent and non-Se-dependent GSH-Px activity, the Se-dependent enzyme activity was generally lower for calves fed 0.03 microgram of Se/g of total solids as compared with activity in calves fed larger amounts of Se. The tissue ranking of non-Se-dependent GSH-Px activity, as a percentage of total GSH-Px activity, was not changed by differences in the Se content of the diets fed to the calves.