Open Accessω‐ and (ω‐1)‐Oxidation of Fatty Acids by Rat Liver Microsomes
Author(s) -
Björkhem Ingemar,
Danielsson Henry
Publication year - 1970
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1970.tb01186.x
Subject(s) - stearate , chemistry , microsome , hydroxylation , organic chemistry , nad+ kinase , chromatography , biochemistry , enzyme
Rat liver microsomes fortified with NADPH catalyzed the conversion of laurate, palmitate and stearate into the corresponding ω‐ and (ω‐1)‐hydroxy derivatives. In addition, small amounts of the dicarboxylic acids were formed from palmitate and stearate. The ratio between ω‐ and (ω‐1)‐oxidized products was about 1 in incubations with laurate, about 2 in those with palmitate and about 3 in those with stearate. Addition of NAD to incubations with palmitate and stearate increased the relative amount of dicarboxylic acids and also the total yield of ω‐oxidized products showing the presence in microsomes of ω‐hydroxy‐fatty acid dehydrogenases. This conclusion was confirmed by the finding that 16‐[1‐ 14 C]hydroxypalmitic acid and 18‐[9,10‐ 3 H 2 ]hydroxystearic acid were converted efficiently into the corresponding dicarboxylic acids by the microsomal fraction fortified with NAD. The same reactions occurred also in the presence of the 1 × g supernatant fluid. The microsomal fraction fortified with NAD as well as the 1 x g supernatant fluid were found to catalyze the oxidation of 17‐hydroxystearic acid into 17‐oxostearic acid. Administration of phenobarbital had no significant effect on microsomal ω‐hydroxylation of laurate, whereas ω‐hydroxylation of palmitate and stearate was inhibited. (ω‐1)‐Hydroxylation of laurate, palmitate and stearate was stimulated about two to three‐fold. Carbon monoxide inhibited ω‐ as well as (ω‐l)‐hydroxylation of laurate, palmitate and stearate.