Human peroxisomal 3-oxoacyl-coenzyme A thiolase deficiency.
We investigated the peroxisomal beta-oxidation system in liver from a patient with clinical features similar to those in the cerebrohepatorenal (Zellweger) syndrome and with elevated levels in body fluids of very-long-chain fatty acids and intermediates in the biosynthesis of bile acids. The peroxisomal beta-oxidation of fatty acids, measured as the cyanide-insensitive formation of [14C]acetyl units from [14C]palmitoyl-CoA, was very low in the patient (less than 10% of the values in control subjects). Immunoblotting experiments using antibodies to peroxisomal beta-oxidation enzymes indicated that peroxisomal 3-oxoacyl-CoA thiolase (acyl-CoA:acetyl-CoA C-acyltransferase, EC 2.3.1.16) was deficient. Addition of purified rat-liver peroxisomal 3-oxoacyl-CoA thiolase to a reaction mixture containing liver homogenate from the patient restored peroxisomal beta-oxidation. We conclude that the deficiency of peroxisomal 3-oxoacyl-CoA thiolase is responsible for the very low peroxisomal beta-oxidation activity and for the accumulation of very-long-chain fatty acids and intermediates in the biosynthesis of bile acids. Furthermore, the finding that both very-long-chain fatty acids and abnormal bile acids accumulate in this patient suggests that a single peroxisomal 3-oxoacyl-CoA thiolase is involved in the oxidative chain shortening of both very-long-chain fatty acids and the coprostanoic acids.
D000102:Acetyl-CoA C-Acyltransferase / Q000172:deficiency* / Q000378:metabolism; D000217:Acyltransferases / Q000172:deficiency*; D002374:Catalase / Q000378:metabolism; D003605:D-Amino-Acid Oxidase / Q000378:metabolism; D005260:Female; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D006801:Humans; D007223:Infant; D008099:Liver / Q000201:enzymology*; D008830:Microbodies / Q000201:enzymology*
D002374:Catalase; D005969:Glutamate Dehydrogenase; D003605:D-Amino-Acid Oxidase; D000217:Acyltransferases; D000102:Acetyl-CoA C-Acyltransferase