In this study we have demonstrated that rat hepatic peroxisomes catalyse the formation of nafenopin-CoA. The process is mediated by apparent high affinity (Km 6.7 μM), low capacity (Vmax 0.31 nmol/mg/min) and low affinity, high capacity isoforms. Palmitic acid (Ki 1.1 μM), r(-) ibuprofen (Ki 7.9 μM), ciprofibrate (Ki 60.2 μM) and clofibric acid (Ki 86.8 μM) competitively inhibited nafenopin-CoA formation catalysed by the apparent high affinity isoform. An antibody raised against the microsomal palmitoyl-CoA ligase inhibited the equivalent peroxisomal enzyme significantly (P < 0.001) but did not inhibit peroxisomal nafenopin-CoA ligase activity. These data suggest that nafenopin-CoA formation is catalysed by a peroxisomal CoA ligase which differs from the peroxisomal long chain fatty acid-CoA ligase in relation to its xenobiotic/antibody inhibitor profile and kinetic characteristics.
- hepatic peroxisomes
- nafenopin-CoA ligase
- palmitic acid, long chain fatty acid-CoA ligase
- xenobiotic carboxylic acids