Studies on peroxisomes. IX. Biochemical effects of simfibrate on precursor incorporation into polypeptide associated with peroxisome proliferation in rat liver.

Treatment with 1,3-propanediol-bis(2-p-chlorophenoxy-isobutyrate) (simfibrate), a hypolipidemic drug, showed little effect on liver weight and hepatic lipid level. When the effects of simfibrate on rat liver peroxisomal enzymes were examined, it was found that cyanide-insensitive fatty acyl-CoA oxidizing system and carnitine acetyltransferase activity increased from 0.38 U/g liver to 4.5 U/g liver and from 227 U/g liver to 6,450 U/g liver, respectively. The activity of D-amino acid oxidase decreased from 1.05 U/g liver to 0.39 U/g liver. Other peroxisomal enzymes including catalase and urate oxidase were not significantly changed by this drug. Of the protein components of the light mitochondrial fraction of simfibrate-treated rat liver, a polypeptide with a molecular weight of approximately 76,000, which has been suggested to be one of the peroxisomal proteins, increased in the treated rat liver (as estimated by sodium dodecylsulfate-polyacrylamide gel electrophoresis) and DL-[4,5-3H]leucine-incorporation into this particular component was also stimulated to a level about 3 times that of the control.