AMINE OXIDASE .14. ISOLATION AND CHARACTERIZATION OF MULTIPLE BEEF LIVER AMINE OXIDASE COMPONENTS

By modifying a previously published purification procedure, three fractions of liver mitochondrial amine oxidase were isolated in sufficient yields to characterize them. All components were bright yellow and showed a pH optima near 9.2. None of the components was inhibited by aldehyde reagents and all components showed similar substrate specificities. The sedimentation coefficients were 14.4 and 20.6, and the molecular weights about 405,000 and 1,280,000, respectively, for components 1 and 2. Component 1 contained 4 and component 2 contained 12 FAD or FAD-like substance per mole of enzyme. In addition, components 1 and 2 contained 24 and 106 moles of phospholipid per mole of enzyme, respectively. The studies indicate that a part of the multiplicity of the enzyme reported by other workers is due to the isolation of the enzyme in different molecular weight forms. In fact component 2 may be a trimer of component 1. Since the higher molecular weight form has a higher specific activity as well as a higher phospholipid content, it may represent a larger fragment from the outer membrane of the mitochondria. © 1969.