Abstract：
We report the gelation of mixed proteins consisting of oppositely charged lysozyme and serum albumins at various pH. The results from rheological tests showed that at a pH of 7, the gelation temperature (Tgel) of the oppositely charged proteins was lower than the melting temperature (Tm) of the individual protein. To ascertain the conformational state of the proteins at the observed Tgel, the attenuated total-reflectance Fourier-transform infrared (ATR-FTIR) spectra of the proteins were acquired. The recorded spectra showed that the proteins were predominantly alpha helical, suggesting that the observed gelation was electrostatically triggered. However, as the solution pH was changed to acid or alkaline regime, all the proteins became similarly charged and showed Tgel < Tm which was attributed to pH-induced denaturation. Surprisingly, however, the serum albumins were remarkably stable at the alkaline pH of 9 and 10 but very labile at the acidic pH. In contrast, the LYZ was more stable at the acidic than alkaline pH. To understand the role of the opposite charges in the gelation, coarse-grained molecular dynamics (CGMD) simulations revealed an increase in the aggregation of the oppositely charged proteins compared with the pure or similarly charged protein mixture.
摘要：
我们报告了在各种pH下由带相反电荷的溶菌酶和血清白蛋白组成的混合蛋白质的凝胶化。流变学测试的结果表明，在pH为7时，带相反电荷的蛋白质的胶凝温度（Tgel）低于单个蛋白质的解链温度（Tm）。为了确定观察到的Tgel上蛋白质的构象状态，获得了蛋白质的衰减全反射傅里叶变换红外（ATR-FTIR）光谱。记录的光谱显示蛋白质主要是α螺旋，表明观察到的凝胶化是静电触发的。然而,当溶液的pH值变为酸性或碱性时，所有的蛋白质变得带类似的电荷并且显示Tgel
