Identification of the cytochrome P450 enzymes responsible for the ω-hydroxylation of phytanic acid

Patients suffering from Refsum disease have a defect in the α-oxidation pathway which results in the accumulation of phytanic acid in plasma and tissues. Our previous studies have shown that phytanic acid is also a substrate for the ω-oxidation pathway. With the use of specific inhibitors we now show that members of the cytochrome P450 (CYP450) family 4 class are responsible for phytanic acid ω-hydroxylation. Incubations with microsomes containing human recombinant CYP450s (Supersomes™) revealed that multiple CYP450 enzymes of the family 4 class are able to ω-hydroxylate phytanic acid with the following order of efficiency: CYP4F3A > CYP4F3B > CYP4F2 > CYP4A11.