FATTY-ACID OMEGA-HYDROXYLATION AND (OMEGA-1)-HYDROXYLATION IN RABBIT INTESTINAL-MUCOSA MICROSOMES

Abstract

Microsomes from rabbit intestinal mucosa washed quickly and thoroughly with phenylmethylsulfonyl fluoride catalyzed fatty acid hydroxylation in the presence of NADPH and molecular oxygen. Myristic and palmitic acids were converted to the corresponding .omega. and (.omega.-1)-hydroxy fatty acids: lauric acid was converted only to 12-hydroxylauric acid, and capric acid, to 9- and 10-hydroxycapric acids together with an unknown polar acid. Among these fatty acids, both myristic and lauric acids appeared to be the most efficient substrates. The inhibition of the hydroxylation by SKF 525-A [.alpha.-phenyl-.alpha.-propylbenzeneacetic acid, 2-(diethylamino)ethyl ester hydrochloride] and Co suggested that the activity depended upon cytochrome P-450. The specific activity of the fatty acid hydroxylation was almost constant along the small intestine, while the aminopyrine N-demethylation activity and the cytochrome P-450 content were highest at the proximal end of the intestine and progressively declined toward the caudal end. The cytochrome P-450 was solubilized from the intestinal microsomes and purified by 6-amino-n-hexyl Sepharose 4B chromatography. The partially purified cytochrome P-450 was active in fatty acid hydroxylation in combination with intestinal NADPH-cytochrome c reductase and phosphatidylcholine.