Sharma M, Joshi P G, Joshi N B
Department of Biophysics, National Institute of Mental Health and Neuro Sciences, Bangalore, India.
Biochim Biophys Acta. 1997 Jan 31;1323(2):272-80. doi: 10.1016/s0005-2736(96)00195-2.
Photodynamic action of merocyanine 540 (MC540) on the plasma membrane of human glioblastoma(U-87MG) cells has been investigated. Plasma membrane was labeled with lipid specific probe 1,(4-trimethylammonium),6-diphenyl-1,3,5-hexatriene. Steady-state anisotropy, decay time and time-dependent anisotropy of TMA-DPH in U-87MG cells have been measured as a function of light dose. A decrease in the steady-state anisotropy and decay time of TMA-DPH in MC540-treated cells was observed upon light irradiation. The time-dependent anisotropy measurements showed a decrease in the limiting anisotropy (r infinity) and an increase in the rotational relaxation time (phi) of the probe upon photosensitization of cells. Analysis of these data using wobbling in cone model for probe rotation in the membrane indicated an increase in the cone angle (theta c) and a decrease in the order parameter (S). Protein specific probe N-(1-pyrene)-maleimide was used to study the effect of photosensitization on the plasma membrane proteins. An increase in the rotational relaxation time and a decrease in the ratio of excimer to monomer fluorescence intensity of PM was observed on photosensitization. Photodynamic action of MC540 also caused an inhibition of protein SH groups and Na(+)-K(+)-ATPase activity of plasma membrane. Our results demonstrate that the photodynamic action of MC540 decreases the order of the lipid bilayer and reduces the mobility of the proteins in the plasma membrane of cells.
研究了部花青540（MC540）对人胶质母细胞瘤（U - 87MG）细胞质膜的光动力作用。用脂质特异性探针1,（4 - 三甲基铵）,6 - 二苯基 - 1,3,5 - 己三烯标记质膜。测量了U - 87MG细胞中TMA - DPH的稳态各向异性、衰减时间和时间依赖性各向异性随光剂量的变化。光照后，观察到MC540处理细胞中TMA - DPH的稳态各向异性和衰减时间降低。时间依赖性各向异性测量表明，细胞光敏化后，探针的极限各向异性（r∞）降低，旋转弛豫时间（φ）增加。使用膜中探针旋转的圆锥摆动模型对这些数据进行分析表明，圆锥角（θc）增加，序参数（S）降低。使用蛋白质特异性探针N -（1 - 芘）- 马来酰亚胺研究光敏化对质膜蛋白的影响。光敏化后，观察到旋转弛豫时间增加，质膜的准分子与单体荧光强度比降低。MC540的光动力作用还导致质膜蛋白质SH基团的抑制和Na（+）-K（+）-ATP酶活性的抑制。我们的结果表明，MC540的光动力作用降低了脂质双层的有序性，并降低了细胞溶质膜中蛋白质的流动性。
