PURIFICATION AND PROPERTIES OF MITOCHONDRIAL MONOAMINE OXIDASE IN BEEF BRAIN

Abstract— Monoamine oxidase was purified approximately 40-fold from beef brain mitochondria. The purification procedure involved extraction with a non-ionic detergent (Nonion NS-210) after heat treatment, ammonium sulphate fractionation, chromatographies on DEAE-cellulose and Sepharose 6B, and a continuous flow electrophoresis. A major component (enzyme 1) with a higher specific activity and a minor component (enzyme 2) with a lower specific activity were separated. Properties of both enzymes towards kynuramine including pH-optimum and K_m values were similar, but the enzyme 1 had the higher specific activity towards tyramine whereas that of enzyme 2 was towards normetane-phrine. Fluorescence spectra indicated that the enzyme 1 is a flavoprotein. Copper was not detected, and copper chelating agents did not inhibit the enzyme. p -Chloromercuribenzoate and JV-ethylmaleimide inhibited the enzyme, indicating the presence of the essential SH-groups.