Effects of vitamin E deficiency on the activities of lipid-requiring enzymes in rabbit liver and muscle

Abstract

The effects of vitamin E deficiency on membrane integrity were studied by examining the temperature dependence of membrane-bound enzyme activities in liver mitochondria and microsome and in muscle sarcoplasmic reticulum. In vitamin E-deficient rabbits, the specific activities at 37°C of mitochondrial oligomycin-sensitive ATPase (EC 3.6.1.3), β-hydroxybutyrate dehydrogenase (EC 1.1.1.30), and microsomal glucose-6-phosphatase (EC 3.1.3.9) were increased, whereas those of microsomal NADH cytochrome C reductase (EC 1.6.99.3) and sarcoplasmic reticulum Ca-ATPase were reduced in comparison to control rabbits. Arrhenius plots of activity against temperature yielded a linear plot over the range 10 to 40°C in the case of β-hydroxybutyrate dehydrogenase, NADH cytochrome C reductase and oligomycin-sensitive ATPase. In control rabbits, all five enzymes showed a single discontinuity in the Arrhenius plot over the range 16 to 19°C. These results reflect changes to the microenvironment of membrane-bound enzymes as a consequence of vitamin E depletion.