The in vitro ω-Oxidation of Phytanic Acid and Other Branched Chain Fatty Acids by Mammalian Liver

Abstract

Try, K. The in vitro ω-Oxidation of Phytanic Acid and Other Branched Chain Fatty Acids by Mammalian Liver. Scand. J. clin. Lab. Invest. 22, 224-230, 1968.

Branched chain fatty acids including phytanic acid can be ω-oxidized by a combined supernatant/micro-some fraction from liver, previously shown to ω-oxidize straight chain fatty acids. Substitutions at the α-end and also in the middle of the fatty acid molecule counteract the initial hydroxylation reaction in the ω-oxidation mechanism. Since the tertiary butyl group in the 3,14,14-trimethylpentadecanoic acid is ω-oxidized, the initial hydroxylation reaction can proceed without the introduction of a double bond. Substitutions at the α-end of the molecule do not prevent the initial hydroxylation at the α-end, but inhibit the further oxidation to a dicarboxylic acid. Phytanic acid is ω-oxidized at a very low rate in mammals. In patients with Refsum's disease where the α-oxidation mechanism is afflicted, the ω-oxidation pathway is not sufficient for the degradation of the small amounts of phytanic acid present in the ordinary diet. The ω-oxidation pathway may, however, be of importance in the limited degradation of phytanic acid in patients with Refsum's disease.

Key Words:

• Branched chain fatty acids
• inborn error of metabolism
• lipid metabolism
• phytanic acid
• Refsum's disease