Monoamine oxidaseに関する研究-21-Sodium cholateのラット肝臓mitochondriaおよびMAOに対する作用

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Many reports have been complained about the difficulty of purification of Monoamine Oxidase (MAO) because of its tight biuding with mitochondria. In process for purification of mitochondrial MAO, solubilization of enzyme has been to proceed before its extraction, and many detergents such as sodium cholate have been used for its purpose. In present paper, effects of sodium cholate which was used for the solubilization of enzyme as a detergent in our laboratory, were studied on isolated rat liver mitochondria using electron microscope and on the relationship between MAO activity and its solubilization. Following results were obtained: 1) At concentrations of less than 1 × 10-3 M, sodium cholate showed no effect on MAO activity. At concentrations of 3 × 10-3 M and 1 × 10-2 of sodium cholate, MAO activities were about 93% and 83% of the control activity, respectively. At concentrations of 3 × 10-2 M and 5 × 10-2 M, MAO activities were about 23% and 7% of the control activity, respectively. 2) Thirty minutes after addition of sodium cholate to mitochondrial preparation at 0°C, the mixtures were centrifuged at 8, 500 × g for 20 minutes. When 1 × 10-3 M and 1 × 10-4 M of sodium cholate were added, 3-6% of total MAO activity was found in supernatant fraction. At a concentration of 1 × 10-2 M of sodium cholate, about 30% of total MAO activity was found in supernatant fraction. 3) Thirty minutes after addition of sodium cholate to the mitochondrial preparation at 0°C, the mixtures were centrifuged at 8, 500 × g for 20 minutes. The precipitate was fixed with OsO4 and its morphological changes were observed using electron microscope. In the control, orthodox conformation form in 2/3 out of total number of mitochondria, and swollen one in 1/3 were observed. The condenced conformation form of mitochondria were observed seldomly. At a concentration of 1 × 10-4 M of sodium cholate, the spaces between outer and inner membranes were widely spreaded, and lack of matrix and its uniformity were observed. Electron densities of matrix and cristae were shown almost similar to the control. At a concentration of 1 × 10-3 M, irreguler shaped and swollen mitochondria were observed. Lack of cristae and decrease of electron density in matrix were observed in about a half of mitochondria. At a concentration of 1 × 10-2 M, various irregular-shaped membranes were observed in outer and inner membrane. The membranes were clearly splitted and the spaces between outer and inner membranes became to 3-5 times of the control. Matrix was disappeared and ghosts of mitochondria were observed in most of mitochondria. To make clear the relationships between the disappearance of matrix, swelling of cristae and shift of MAO activity from mitochondria to soluble fraction, further study is needed.
学校法人昭和大学・昭和医学会の論文

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豊島良枝
昭和大学医学部第二薬理学教室

Monoamine oxidaseに関する研究-21-Sodium cholateのラット肝臓mitochondriaおよびMAOに対する作用

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