Properties and Subcellular Localization of Myocardial Fatty Acyl-coenzyme A Oxidase

Authors

Earl H. Harrison
Mbaga S. Walusimbi, Wright State UniversityFollow

Document Type

Article

Publication Date

9-1988

Abstract

The properties and subcellular localization of fatty acyl-CoA oxidase (FAO) were studied in rat heart homogenates. After differential centrifugation, FAO was sedimentable and enriched in a “light-mitochondrial” fraction. FAO had a pH optimum of 8–9. Among straight-chain, saturated fatty acyl-CoAs, the enzyme showed a marked preference for medium chain substrates (C₁₂ > C₁₀ = C8 > C₁₆ = C₁₄ > C₆) over a concentration range up to 100 µM. No activity was observed with C₄-CoA. The apparent Michaelis constant (K_m) for C₁₂-CoA was 5-10 µM. After removal of nuclei by low-speed centrifugation, combined subcellular particle preparations were obtained by high-speed centrifugation and layered on linear density gradients of metrizamide. After density equilibration, FAO showed a symmetric distribution centered at ρ = 1.16–1.18, like that of the enzyme catalase, a marker for microperoxisomes. In contrast, enzyme markers for mitochondria, lysosomes, sarcolemma, and sarcoplasmic reticulum were recovered in low-density regions of the gradient. These results provide a direct demonstration of fatty acyl-CoA oxidase in cardiac tissue and its association with microperoxisomes.

Repository Citation

Harrison, E. H., & Walusimbi, M. S. (1988). Properties and Subcellular Localization of Myocardial Fatty Acyl-coenzyme A Oxidase. American Journal of Physiology, 255 (3), H441-H445.
https://corescholar.libraries.wright.edu/surg/190