α-Oxidation pathway. The figure represents the recently revised α-oxidation pathway for phytanic acid, including the results of this paper. The enzymes involved are: 1, phytanoyl-CoA synthetase; 2, phytanoyl-CoA hydroxylase; 3, 2-HPCL; 4, branched fatty aldehyde dehydrogenase; and 5, formyl-CoA hydrolase.