Stereochemistry of the peroxisomal branched-chain fatty acid α- and β-oxidation systems in patients suffering from different peroxisomal disorders

• Main Authors: S. Ferdinandusse, H. Rusch, A.E.M. van Lint, G. Dacremont, R.J.A. Wanders, P. Vreken
• Format: Article
• Language: English
• Published: Elsevier 2002-03-01
• Series: Journal of Lipid Research
• Subjects: phytanic acid; pristanic acid; trimethylundecanoic acid; peroxisomal fatty acid oxidation disorders; diastereomers; (R)-1-phenylethylamine
• Online Access: http://www.sciencedirect.com/science/article/pii/S0022227520301504

Phytanic acid (3,7,11,15-tetramethylhexadecanoic acid) is a branched-chain fatty acid derived from dietary sources and broken down in the peroxisome to pristanic acid (2,6,10,14-tetramethylpentadecanoic acid) via α-oxidation. Pristanic acid then undergoes β-oxidation in peroxisomes. Phytanic acid naturally occurs as a mixture of (3S,7R,11R)- and (3R,7R,11R)-diastereomers. In contrast to the α-oxidation system, peroxisomal β-oxidation is stereospecific and only accepts (2S)-isomers. Therefore, a racemase called α-methylacyl-CoA racemase is required to convert (2R)-pristanic acid into its (2S)-isomer. To further investigate the stereochemistry of the peroxisomal oxidation systems and their substrates, we have developed a method using gas-liquid chromatography-mass spectrometry to analyze the isomers of phytanic, pristanic, and trimethylundecanoic acid in plasma from patients with various peroxisomal fatty acid oxidation defects. In this study, we show that in plasma of patients with a peroxisomal β-oxidation deficiency, the relative amounts of the two diastereomers of pristanic acid are almost equal, whereas in patients with a defect of α-methylacyl-CoA racemase, (2R)-pristanic acid is the predominant isomer. Furthermore, we show that in α-methylacyl-CoA racemase deficiency, not only pristanic acid accumulates, but also one of the metabolites of pristanic acid, (2,6,10)-trimethylundecanoic acid, providing direct in vivo evidence for the requirement of this racemase for the complete degradation of pristanic acid. —Ferdinandusse, S., H. Rusch, A. E. M. van Lint, G. Dacremont, R. J. A. Wanders, and P. Vreken. Stereochemistry of the peroxisomal branched-chain fatty acid α- and β-oxidation systems in patients suffering from different peroxisomal disorders.