ω-Oxidation of Fatty Acids

The oxido-reduction of 17-hydroxystearic acid by enzymes present in the microsomal and soluble fractions of homogenates of rat and guinea pig liver was studied.The rate of oxidation of L-17-hydroxystearic acid into 17-ketostearic acid by the 100,000 X g supernatant fluid of rat and guinea pig liver homogenate was 2.2 and 6 times, respectively, faster than the rate of oxidation of D-17-hydroxystearic acid.In the presence of microsomal fraction of rat liver homogenate, D-17-hydroxystearic acid was oxidized 1.4 times faster than L-17-hydroxystearic acid.Reduction of 17-ketostearic acid by the 100,000 X g supernatant fluid of rat and guinea pig liver homogenate yielded 17-hydroxystearic acid of which 72% and 91%, respectively, was the L-17-enantiomer.Reduction by the microsomal fraction of rat liver homogenate yielded 68% of D-17-and 32% of L-17-hydroxystearic acids.The soluble enzyme was found to utilize the 4A-hydrogen in NADPH whereas the microsomal enzyme utilized the 4Bhydrogen in NADH.