标题：Coenzyme A-dependent modification of fatty acyl chains of rat liver membrane phospholipids: possible involvement of ATP-independent acyl-CoA synthesis.
出版社：American Society for Biochemistry and Molecular Biology
摘要：Certain species of fatty acyl chains of microsomal lipids from rat hepatocytes underwent desaturation when the microsomal fraction was incubated with CoA and NADH. For instance, 18:0, 18:2(n-6), and 20:3(n-6) incorporated into membrane lipids were gradually converted to 18:1(n-9), 18:3(n-6), and 20:4(n-6), respectively. Further, 20:5(n-3) and 18:3(n-6) were metabolized to 22:5(n-3) and 20:4(n-6) respectively, through chain elongation or chain elongation plus subsequent desaturation when malonyl-CoA was present. In contrast to esterified fatty acids, negligible change was observed for fre fatty acids under the same experimental conditions. It is apparent that ATP-independent acyl-CoA synthesis is implicated in such enzymatic modification of fatty acyl chains. The presence of either gel-filtered cytosol or bovine serum albumin markedly potentiated the reaction. However, the addition of ATP and Mg2+ did not accelerate the overall reaction induced in the presence of CoA alone. These results suggest that the pathway of CoA-dependent/ATP-independent modification of fatty acyl chains is sufficiently active to account for the desaturation and chain elongation of fatty acids esterified in membrane lipids, especially phospholipids, of living cells.
