Mikes V, Dadák V
Biochim Biophys Acta. 1983 May 27;723(2):231-9. doi: 10.1016/0005-2728(83)90122-6.
The interaction of rat liver and bovine heart mitochondria with a series of fluorescent, cationic berberine derivatives varying in the length of alkyl chain has been investigated. An increase in the hydrophobicity of the derivative was accompanied by a larger value of the partition coefficient and by binding to a more hydrophobic region of the inner mitochondrial membrane. It was found that berberines could be used as sensitive indicators of processes which take place on the outer surface of the mitochondrial membrane; the greatest (15-fold) increase in fluorescence was obtained with 13-methylberberine in the energized state of mitochondria. The fluorescence increase was due to the increase in fluorescence quantum yield although a small increase in the amount of bound derivative could also be detected upon energization. The fluorescence was linearly dependent on the magnitude of the membrane potential. In parallel with an observed fluorescence enhancement a considerable decrease in rotational mobility was found. We suggest that berberines move in the inner membrane according to the polarity of the membrane potential; consequently, deeper immersion in the less polar region in the energized state brings about a larger fluorescence increase. More hydrophobic derivatives inhibited NAD-linked respiration in rat liver mitochondria but exerted no effect on succinate oxidation up to 10 microM concentration.
研究了大鼠肝脏和牛心脏线粒体与一系列烷基链长度不同的荧光阳离子黄连素衍生物之间的相互作用。衍生物疏水性的增加伴随着分配系数值的增大以及与线粒体内膜更疏水区域的结合。发现黄连素可用作线粒体外膜上发生过程的灵敏指示剂；在线粒体的激发态下，13-甲基黄连素的荧光增强最大（15倍）。荧光增强是由于荧光量子产率的增加，尽管在激发时也能检测到结合衍生物量的少量增加。荧光与膜电位大小呈线性相关。与观察到的荧光增强同时，发现旋转流动性显著降低。我们认为黄连素根据膜电位的极性在内膜中移动；因此，在激发态下更深地浸入极性较小的区域会导致更大的荧光增强。疏水性更强的衍生物抑制大鼠肝脏线粒体中与NAD相关的呼吸作用，但在浓度高达10 microM时对琥珀酸氧化没有影响。
