CHAIN-LENGTH SPECIFICITIES OF PEROXISOMAL AND MITOCHONDRIAL BETA-OXIDATION IN RAT-LIVER

The β-oxidation system for fatty acids and the novel fatty acyl-CoA oxidase activity of liver peroxisomes were characterized in terms of assay requirements and of chain length specificity of substrate. Both activities showed a specificity for medium to long-chain length acyl-CoA's (C10-C16), with a well defined peak of activity at C12. The specific activities were similar and, in each case, oleoyl-CoA was a better substrate than stearoyl-CoA. The mitochondrial fatty acyl-CoA dehydrogenase activity showed a broader range (C4-C16), with the shorter-chain length substrate being the more active and no preference being shown for oleoyl-over stearoyl-CoA. Using palmitoyl-CoA as substrate, the total enzymatic activity for the first step of β-oxidation in the mitochondrion was 7.7-fold greater than for the corresponding step in the peroxisome. © 1979 Academic Press, Inc. All rights of reproduction in any form reserved.