A kinetic model for the effects of vanadate on human erythrocyte membrane

The effects of vanadate on human erythrocyte membrane have been investigated with stopped-flow and equilibrium fluorescence quenching techniques. The equilibrium study showed a half-quenching concentration(K 1/2 ) of 0.27 mmol.L-1. The stopped-flow experiment exhibited a fast rise (tsk1/f1 S) and a slow drop (tin 1~2 min) in fluorescence. Based on the results and that from the across membrane transport of vanadate, a kinetic model is proposed which suggests that the membrane proteins experience a series of conformational changes before and during the quenching of the intrinsic fluorescence. These changes are induced mainly by three kinds of interactions: (i) the long-distance, non-specific interaction between the vanadate and the erythrocyte membrane surface, (ii) the charge interaction between the vanadate and parts of the membrane proteins, and(iii) the binding of the vanadate to some membrane proteins.

黄芪对人红细胞膜脂流动性及膜蛋白构象的影响

用荧光偏振、圆二色谱(CD)和准弹性光散射等实验技术研究了中药黄芪对人红细胞膜的作用。黄芪能增加人红细胞膜脂流动性,增加膜蛋白中α-螺旋的含量,对膜表面电荷也有影响。黄芪对膜蛋白的作用比对膜脂作用更敏感。黄芪对人红细胞膜作用的一个重要环节可能是保护人红细胞膜免受自由基的攻击。

甲基毒死蜱对红细胞膜乙酰胆碱酯酶的抑制作用及其与膜脂相互关系

以人红细胞膜为材料,研究了甲基毒死蜱与膜上乙酰胆碱酯酶(AChE)的相互作用及其与膜脂的关系。结果显示,甲基毒死蜱对人红细胞膜AChE有明显的抑制作用,与膜温育30min,其半数抑制浓度约为0.10 mmol/L。动力学分析表明,其抑制作用为非竞争性。0.2％Triton X-100并不改变AChE对甲基毒死蜱的敏感性,亦即AChE上甲基毒死蜱的作用部位与其所处的脂质微环境无关。

丙溴磷对人红细胞膜的毒性作用

为探讨丙溴磷对人红细胞膜的毒性作用 ,检测了红细胞膜Ⅰ型补体受体 (Em -CR1)免疫粘附肿瘤细胞活性与红细胞超氧化物歧化酶 (E -SOD)活性、红细胞膜唾液酸 (Em -SA)含量以及红细胞膜脂流动性。结果发现 ,一定浓度丙溴磷可使上述各项指标显著降低 ,并呈现剂量 -效应关系 。

丁卡因对人红细胞膜乙酰胆碱酯酶的抑制作用及其与膜脂的关系

本文以人红细胞膜为材料，应用荧光探针（ANS）及酶学研究方法，研究了丁卡因对AchE及红细胞膜脂之间的关系。结果显示，丁卡因对红细胞膜AchE有明显抑制作用，其半数抑制浓度为525μmol/L。丁卡因还能増加膜-ANS复合物荧光强度，双倒数及Scatchard作图分析表明，其使膜ANS复合物荧光强度增强的原因并非ANS荧光量子产率的改变，而是膜上ANS结合数量增加所致，这一效应与其时膜流动性影响是一致的。