<原報>ラット脳内 Monoamine Oxidase の局在部位に関する研究

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Four fractions-nuclear, mitochondrial, microsomal and soluble-were separated from whole rat brain homogenate and approx. 61% of MAO activity of whole brain homogenate was demonstrated in mitochondrial fraction. Then, three groups of three mitochondrial membrane fractions-outer membrane, inner membrane and soluble-were prepared by centrifuging after three kinds of treatment (sonication, snake venom phospholipase digestion and defreezing) and the contamination was examined by electron microscopic method. The defreezing method would appear to be more specific for separating the outer membrane fraction than the others. Therefore, the following experiment was done by this method. In the fraction precipitated at 2,000×g for 10min., the elementary particles fixed cristae were observed and only 6% of the mitochondrial MAO activity was found. Seventy three percentage of mitochondrial MAO activity appeared in the fraction precipitated at the range 2,000-10,000×g for 20 min., in which outer membrane was found. No MAO activity could be recognized in the supernatant obtained by centrifuging at 40,000×g for 30min., which was considered to be soluble fraction. These results in the present paper will suggest that MAO is localized in the insoluble fraction of mitochondrial outer membrane.
1975-02-25