甘氨酸促进蛋清溶菌酶形成淀粉样纤维

Glycine promoted amyloid fibrils formation of hen egg-white lysozyme

为了探讨甘氨酸在淀粉样纤维形成中的作用,将模型蛋白蛋清溶菌酶(HEWL)分别置于pH 2.0的甘氨酸和盐酸溶液中,(50±0.1)℃孵育8 d后采用硫磺素T、刚果红荧光、ANS荧光、圆二色谱、透射电子显微镜和Western-blot方法检测HEWL在两种溶液中的纤维生成情况及蛋白表位变化。结果显示:HEWL在pH 2.0甘氨酸溶液中形成了大量短杆状淀粉样纤维,纤维疏水性显著增强,二级结构β-折叠含量提高了27.8%,且特异抗体识别到的蛋白量明显减少,纤维化蛋白的表位已发生改变;而在pH 2.0盐酸溶液中未形成淀粉样纤维。表明酸性溶液中甘氨酸的存在促进了HEWL形成淀粉样纤维,这为解释朊蛋白及其他蛋白形成淀粉样纤维的机制提供了线索。

The aim of this study was to investigate the effect of glycine on amyloid fibrils formation.The hen egg-white lysozyme(HEWL)was separately prepared in acidic glycine and hydrochloric(HCl)solutions of pH 2.0 and incubated at(50±0.1)℃for 8 days.HEWL fibrils were detected by the methods of ThT and Congo red florescence,ANS fluorescence,circular dichroism,transmission electron microscopy,and the change of epitopes of fibrillar protein were detected by Western-blot.The results showed that the great amounts of rod-like HEWL fibrils were formed in acidic glycine solution.the hydrophobicity was greatly increased and theβ-sheet structure was increased by 27.8%.Furthermore,the amounts of protein recognized by the antibody were greatly reduced,and the epitopes of fibrillar HEWL protein were changed.While no amyloid fibrils were formed in acidic hydrochloric solution.These results suggested that the presence of glycine in acidic solution promoted the formation of HEWL fibrils,which provided the clue for the mechanism of amyloid fibrils formation by prion and other proteins.