不同pH环境下Cu2+和Zn2+诱导淀粉样β蛋白聚集作用的研究

摘要

目的 观察生理(pH=7.4)或病理性微酸(pH=6.6)环境下过渡金属离子(Cu2+、Zn2+)对阿尔茨海默病(AD)关键致病分子淀粉样β蛋白(β-amyloid,Aβ)聚集的诱导作用.方法 采用浊度法和考马斯亮蓝上清蛋白测定法观察Cu2+和Zn2+对Aβ1-40聚集的诱导作用.结果 (1)浊度法的结果表明,微酸性pH6.6下,Cu2+和Zn2+在5～20μm的浓度明显诱导Aβ(10μm)聚集,该作用呈剂量相关性;生理pH=7.4环境下,Zn2+在5～20μm的浓度仍能明显诱导Aβ(10μm)聚集,作用呈剂量相关性;而Cu2+在此浓度范围内诱导Aβ聚集作用不明显;(2)考马斯亮蓝上清蛋白测定法的结果显示,在微酸性pH6.6下,Cu2和Zn2+均能剂量依赖性地诱导Aβ聚集,且Cu2+诱导Aβ聚集作用较Zn2+更为明显;与浊度法的结果相似,Cu2+在生理pH7.4环境下诱导Aβ聚集作用不明显,而Zn2+仍能诱导Aβ聚集.结论 (1)Cu2+和Zn2+诱导Aβ聚集的作用具有剂量依赖性;(2)无论在生理或病理性微酸环境下,Zn2+均能够诱导Aβ聚集,而Cu2+对Aβ聚集的诱导作用具有明显的pH依赖性:在病理性微酸环境下能够明显诱导Aβ聚集,而在生理pH下,Cu2+未表现出对Aβ聚集的诱导作用.%Objective To investigate the influence of physiological (pH7. 4) and weak acidic (pH6.6) pH environment on metal ions (cooper and zinc) induced- β-amyloid aggregation by.Methods In this study,using the turbidometric assays and Coomassie brilliant blue protein assay methods to determine the effects of metal ions induced Aβ1-40 aggregation. Results (1)It is determined by turbidity that at pH 6.6,Cu2+ and Zn2+ (5～20 μM) induced aggregation of Aβ 10 μM is dose-dependent.At pH 7.4, the effect of Cu2+ (5～ 20μM) induced aggregation of Aβ 10 μM is not significant, however the effect of Zn2+ (5～20μM) induced aggregation of Aβ 10 μM is dose-dependent. (2) Using Coomassie brilliant blue protein assay, at pH 6.6, Cu2+ and Zn2+ (5 ～ 20 μM) induced the aggregation of Aβ10 μM is dose-dependent,and the aggregation of cooper is higher than zinc. Conclusions (1) Cu2+ and Zn2+ induced β-amyloid aggregation is dose-dependent. (2)In both physiological(pH7.4) and weak acidic(pH6.6) environments Zn2+ are able to induce β-amyloid aggregation. However Cu2+ induced β-amyloid aggregation is significant pH-dependent: in acidic environment(pH6.6) Cu2+ can induce the aggregation of Aβ; but in physiological environment(pH7.4) there is no effect on the induction of aggregation of Aβ.