Molecular Weight Estimation of Bovine Brain Mitochondrial Monoamine Oxidase

Abstract

The molecular size of bovine brain mitochondrial monoamine oxidase (MAO) was investigated. Mitochondria were solubilized with an anionic detergent, Emarl 20C, and fractionated by ammonium sulfate. Ammonium sulfate-fractionated MAO was subjected to detergentcontaining gel chromatography and detergent-containing gel electrophoresis. MAO activity appeared as single symmetrical peak in gel chromatography in the presence of 1% Emarl 20C, and the molecular weight was estimated to be 44, 000. Polymerization of MAO was observed when gel chromatography was performed in lower (0.1%, 0%) concentrations of Emarl 20C. Activity staining of MAO after electrophoresis on a gel containing 0.1% Emar 20C was successful. The molecular weight of MAO estimated from the mobility of this stained band was 89, 000. It is suggested that the molecular weight of MAO is 44, 000 and that it recombines in low concentrations of the detergent to form complex particles with molecular weights of 89, 000 or more.