ω-Oxidation of Fatty Acids

Rat liver microsomes in the presence of NADPH and O2 catalyzed ω1- as well as ω2-hydroxylation of decanoic acid. 10-Hydroxydecanoic acid accounted for 92% of the products formed, l-9-hydroxydecanoic acid for 6% and d-9-hydroxydecanoic acid for 2%. Incubations of [9-2H2]- and [10-2H3]decanoic acids followed by mass spectrometric analyses of the products showed that the hydroxylations occurred with loss of 1 hydrogen atom from the carbon hydroxylated. The two hydroxylations at carbon 9 both proceeded stereospecifically with retention of the absolute configuration. Significant isotope effects were present in the formation of d-9- and l-9-hydroxydecanoic acids from [9-2H2]decanoic acid. The formation of 10-hydroxydecanoic acid from [10-2H3]decanoic acid occurred without isotope effect.