The effect of protein deficiency on some rat liver lipid metabolic enzymes and CoA

Two groups of male Wistar rats were fed normal (i.e., 18%) and protein-free diets, respectively, for 7 weeks. In vivo incorporation of [1-14C] acetate into palmitic, stearic, oleic, and arachidonic acids by the liver was reduced in the protein-deficient rats. In vitro incubation of liver microsomes with labeled palmitate or linoleate revealed no change in the specific activities of chain elongating or desaturating enzymes. Protein deficiency resulted in a decrease in specific activity of short chain acyl-CoA synthetase and in total CoA, accompanied by the virtual disappearance of acyl-CoA and an increase in free CoA. Furthermore, there was less microsomal fatty acid synthetase and mitochondrial beta-hydroxybutyrate dehydrogenase activity. These results are discussed in relation to fatty acid synthesis and the changes in liver fatty acid composition.