Glass transition and dynamics of molecules in partially crystallized aqueous solution of protein

在113 ~ 300 K温度范围内，用宽带介电谱技术，在1 mHz ~ 50 GHz频率范围内，对明胶、牛血清白蛋白（BSA）和溶菌酶与水的混合物进行了研究，观察到了三种不同的弛豫过程。非结晶水和水合蛋白质的弛豫过程的特征性质与在各种非结晶水溶液中观察到的特征性质相同。冰的融化对水合明胶的松弛过程的影响大于对水合BSA和溶菌酶的影响。在整个浓度范围内澄清的玻璃化转变，熔融和结晶温度在BSA和溶菌酶-水的混合物的浓度依赖性。在聚醋酸乙烯酯-苯和聚丙烯酸乙酯-对二甲苯的混合物中，由于溶剂的熔融和结晶引起的缩聚和增塑，导致聚合物局部链运动的弛豫时间的突变和玻璃化转变，以及非结晶溶剂的存在得到了证实。这意味着水和聚合物之间的氢键是不必要的在零度以下的温度下的非结晶水的存在。

Three kinds of relaxation processes originated from uncrystallized water, ice, and hydrated protein were observed using broadband dielectric spectroscopyat temperatures between 113K and 300K in a frequency range of 1 mHz - 50 GHz for water mixtures with gelatin, bovine serum albumin (BSA), and lysozyme. The characteristic properties of the relaxation processes of uncrystallized water and hydrated protein were common to those observed in various kinds of non-crystallized aqueous solutions. Theinfluence of the melting of ice for the relaxation process of hydrated gelatin is larger than that of the hydrated BSA and lysozyme. The concentration dependences of the glass transition, melting, and crystallization temperatures in BSA- and lysozyme-water mixtures were clarified in entire concentration range. The glass transition and abrupt change of the relaxation time of the local chain motion of polymers caused by the condensation and plasticization induced by the melting and crystallization of solvents where observed in the mixtures of poly (vinyl acetate)-benzene and poly (ethyl acrylate)-p-xylene, and presence of the non-crystallized solvents were confirmed. It implies that the hydrogen-bond between water and polymer is not necessary for the presence of uncrystallized water at subzero temperatures.