Abstract
Peroxisomes as well as mitochondria are capable of fatty acid β-oxidation. Studies over the last few years have shown that the two β-oxidation systems display different substrate specificities. Indeed, mitochondria are primarily involved in the oxidation of short-, medium- and long-chain fatty acids (Pollitt 1995), whereas peroxisomes are the sole site of very long-chain fatty acid oxidation. Furthermore, the first cycle of β-oxidation of the branched-chain fatty acid pristanic acid (2,6,10,14-tetramethylpentadecanoic acid) and the bile acid intermediates di- and trihydroxycholestanoic acid occurs solely in peroxisomes (Reddy and Mannaerts 1994). Unfortunately, the interaction between the two β-oxidation systems has received little attention. Since peroxisomes are incapable of oxidizing fatty acids to completion, it is clear that very long-chain fatty acids (e.g. C 26 :0 ) and pristanic acid will only undergo a limited number of β-oxidation cycles within the peroxisomes, after which transport to the mitochondrion takes place. Furthermore, it is unknown at present how many cycles of β-oxidation occur in peroxisomes. Since this may also be of significance for the pathogenesis of long-chain fatty acid β-oxidation disorders, we studied the consequences of a defect in mitochondrial β-oxidation on peroxisomal fatty acid β-oxidation. We selected cells from a patient with a deficiency of the mitochondrial carnitine/acylcarnitine carrier as first reported by Pande and co-workers (1993) for this purpose and used cerotic acid (C 26 :0 ) and pristanic acid as established peroxisomal fatty acid substrates.
Published Version
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