Detection of heat-stable δ, δ²-enoyl-coa isomerase in rat liver mitochondria and peroxisomes by immunochemical study using specific antibody

The subcellular distribution of Δ³,Δ²-enoyl-CoA isomerase [EC 5.3.3.8] and the inducing effect of clofibrate, a peroxisomal proliferator, on the enzyme activity were examined in rat liver. From the results of spectrophotometric investigation of the fractions, which were prepared by sucrose discontinuous gradient centrifugation from the light mitochondrial fraction, the isomerase activity was found in the fractions enriched in mitochondria and those enriched in peroxisomes of the control and the clofibrate treated rat livers. The anti-isomerase antibody reacted with both the mitochondrial isomerase and the peroxisomal isomerase, revealing a single band with an apparent molecular weight of 30,000. However, the isomerase was induced by clofibrate administration mainly in the mitochondrial fraction. These results suggest that Δ³,Δ²-enoyl-CoA isomerase is located in the mitochondria and the peroxisomes of the normal rat liver, and that the isomerase in the mitochondria is induced by clofibrate administration.