VERY LONG-CHAIN FATTY-ACIDS IN HIGHER ANIMALS - A REVIEW

Fatty acids with greater than 22 carbon atoms (very long chain fatty a cids, VLCFA) are present in small amounts in most animal tissues. Satu rated and monoenoic VLCFA are major components of brain, while the pol yenoic VLCFA occur in significant amounts in certain specialized anima l tissues such at retina and spermatozoa. Biosynthesis of VLCFA occurs by carbon chain elongation of shorter chain fatty acid precursors whi le beta-oxidation takes place almost exclusively in peroxisomes. Mitoc hondria are unable to oxidize VLCFA because they lack a specific VLCFA coenzyme A synthetase, the first enzyme in the beta-oxidation pathway . VLCFA accumulate in the tissues of patients with inherited abnormali ties in peroxisomal assembly, and also in individuals with defects in enzymes catalyzing individual reactions along the beta-oxidation pathw ay. It is believed that the accumulation of VLCFA in patient tissues c ontributes to the severe pathological changes which are a feature of t hese conditions. However, little is known of the role of VLCFA in norm al cellular processes, and of the molecular basis for their contributi on to the disease process. The present review provides an outline of t he current knowledge of VLCFA including their biosynthesis, degradatio n, possible function and involvement in human disease.