Inhibitory Effect of NaCI on Hog Kidney Mitochondrial Membrane-Bound Monoamine Oxidase: pH and Temperature Dependences

[摘要] References(44)For a further understanding of the inhibitory effect of NaCI on hog kidney mitochondrial monoamine oxidase (MAO), the activity for benzylamine as substrate was assayed spectrophotometrically in the absence and presence of NaCI for mitochondrial outer membrane preparations as well as whole mitochondria. The effect of CaC12 was also examined for comparison. The inhibition by NaCI but not CaC12 was strongly pH dependent. The pH dependence of the inhibitory effect of NaCI in phosphate buffer was parallel to the pH dependence of the MAO activity itself. The point at which the slope of the Arrhenius plot in the absence of NaCl decreases with increasing temperature was to be 32.3°C at pH 7.0 and 30.4°C at pH 7.5 in phosphate buffer, while the Arrhenius plot in the presence of NaCI exhibited discontinuities without change in the slope in small temperature ranges, 39.2°C-40.0°C and 33.0°C-34.2°C. It was estimated that the inhibitory effect of NaCl was due to a pH and temperature sensitive cooperative state change involving MAO protein and boundary lipids, while the effect of CaC12 could be induced by specific Ca2+ binding to acidic phospholipids.

[学科分类] 药理学

[关键词] Hog kidney monoamine oxidase;Whole mitochondria;Mitochondrial outer membrane;Inhibitory effect of NaCl;Arrhenius plot