Partial Separation and Properties of Mitochondrial Monoamine Oxidase in Brain
1966 年 59 巻 6 号 p. 606-612
詳細
1966 年 59 巻 6 号 p. 606-612
1. Monoamine oxidase was partially separated from beef brain mitochondria by the combined effects of the use of a detergent Cutscum (1.2%, , pH 7.1) and of sonication (20 kc, 4 minutes, twice). The activity was followed by the disappearance of kynuramine. About 70% of the original activity was liber-ated into solution after the treatments. The activity stayed in the supernatant after the centrifugation at 105, 000×g for 3 hours. The solubilized preparation was unstable. Rapid separation by DEAE cellulose column chro-matography resulted in only 6-fold purifica-tion from the original homogenate.
2. The properties of solubilized brain monoamine oxidase were examined. The enzyme was found to be a sulfhydryl enzyme in so far as it was inhibited by p-chloro-mercuribenzoate. Some metal chelating agents inhibited the activity. The inhibition by sodium diethyldithiocarbamate and euprizone may be indicative of copper in-volvement as a cofactor. The following biogenic amines besides kynuramine could be deaminated by the solubilized enzyme preparation; tryptamine, serotonin, tyramine, dopamine, norepinephrine, and epinephrine. The pH-activity curve showed an optimum between pH 7.5 and 8.0 when kynuramine was used as substrate. Several inhibitors of monoamine oxidase of therapeutic and pharmacological interest, markedly inhibited the activity at concentrations as low as 1×10-5 M.
The author is grateful to Dr. S. Udenfriend (National Institutes of Health, Bethesda) for his encouragement and valuable suggestions. My thanks are also due to Dr. S. Udenfriend and Dr. M. Levitt
(National Institutes of Health, Bethesda) for gifts of monoamine oxidase inhibitors, to Dr. J.W. Daly (National Institutes of Health, Bethesda) and. Dr. D. E. Wolf (Merck Sharp and Dohme Research Laboratories, Rahway) for gifts of kynuramine dihy-drobromide and Cutscum.
