ACYL-COA SYNTHETASE AND THE PEROXISOMAL ENZYMES OF BETA-OXIDATION IN HUMAN-LIVER - QUANTITATIVE-ANALYSIS OF THEIR SUBCELLULAR-LOCALIZATION
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1984
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Abstract
The presence of acyl CoA synthetase (EC 6.2.1.3) in peroxisomes and the subcellular distribution of .beta.-oxidation enzymes in human liver were investigated by using a single-step fractionation method of whole liver homogenates in metrizamide continuous density gradients and a novel procedure of computer analysis of results. Peroxisomes contain 16% of the liver palmitoyl CoA synthetase activity, and 21% and 60% of the enzyme activity was localized in mitochondria and microsomal fractions, respectively. Fatty acyl CoA oxidase was localized exclusively in peroxisomes, confirming previous results. Human liver peroxisomes contribute 13%, 17% and 11% of the liver activities of crotonase, .beta.-hydroxyacyl CoA dehdyrogenase and thiolase, respectively. The absolute activities found in peroxisomes for the enzymes investigated suggest that in human liver fatty acyl CoA oxidase is the rate-limiting enzyme of the peroxisomal .beta.-oxidation pathway, when palmitic acid is the substrate.