Amine Oxidase
VII. BEEF LIVER MITOCHONDRIAL MONOAMINE OXIDASE, A COPPER-CONTAINING PROTEIN
Sakari Nara 1, Benedict Gomes 1, and Kerry T. Yasunobu 1
From the
1 From the Department of Biochemistry and Biophysics, University of Hawaii, Honolulu, Hawaii 96822
Beef liver mitochondrial monoamine oxidase was purified as much as 58-fold by a procedure involving disruption of the mitochondria by homogenization and Triton X-100 treatment, ammonium sulfate fractionation, alumina gel C
treatment, and chromatography on diethylaminoethyl cellulose. The procedure yielded preparations of the enzyme which were soluble and others which still required detergent for solubility in aqueous solutions.
The substrate specificity, pH optimum, sensitivity to sulfhydryl reagents, and other properties indicated that the purified enzyme is the classical mitochondrial monoamine oxidase.
From the metal analyses of the purified preparations of the enzyme, it was demonstrated that the beef liver monoamine oxidase is a copper-containing protein. The purest preparations contained about 0.07% copper. Other metals known to be present in oxidative enzymes were present in insignificant amounts. The copper was shown to be in the cupric state.
Known copper-chelating agents inhibited the enzyme, and cuprizone was shown to be a mixed inhibitor of the enzyme.
Submitted on October 4, 1965
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