Subterminal Hydroxylation of Fatty Acids by a Cytochrome P-450-Dependent Enzyme System from a Fungus, Fusarium oxysporum

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Abstract
The cell-free extract of a cytochrome P-450-producing fungus, Fusarium oxysporum, was found to catalyze the hydroxylation of fatty acids. Three product isomers were formed from a single fatty acid. The products from lauric acid were identified by mass-spectrometry as 9-, 10-, and 11-hydroxydodecanoic acids, and those from palmitic acid as 13-, 14-, and 15-hydroxyhexadecanoic acids. The ratio of the isomers formed was 50: 36: 14 in the case of laurate hydroxylation, and 37: 47: 16 in the case of palmitate. The reaction was dependent on both NADPH (or NADH) and molecular oxygen, and was strongly inhibited by carbon monoxide, menadione, or the antibody to purified Fusarium P-450. Further, lauric acid induced a type I spectral change in purified Fusarium P-450 with an apparent Kd of 0.3 mM. The hydroxylase activity together with cytochrome P-450 could be detected in both the soluble and microsome fractions, and the activity was almost proportional to the amount of cytochrome P-450 reducible with NADPH. It can be concluded from these results that Fusarium P-450 is involved in the (ω-1)-, (ω-2)-, and (ω-3)-hydroxylation of fatty acids catalyzed by the cell-free extract of the fungus.