Miyakawa K, Totoki M, Kaibara K
Department of Applied Physics, Faculty of Science, Fukuoka University, Japan.
Biopolymers. 1995 Jan;35(1):85-92. doi: 10.1002/bip.360350109.
The quasi-elastic light scattering studies were carried out to investigate effects of metal cations such as Ca2+ and Na+ on the early stage of coacervation process of alpha-elastin, a chemical fragmentation product originated from the biological elastomeric protein elastin, in aqueous solutions. In particular, our attention was focused on changes of two types of dynamical behaviors found in the earlier work, which are a remarkable increase and a monotonous decrease in the hydrodynamic radius R of molecules with temperature for critical and off-critical concentrations of alpha-elastin, respectively. For the critical alpha-elastin concentration, an addition of Ca2+ was found to exert little effects on the steep temperature profile of R observed in the absence of Ca2+. On the other hand, an addition of a slight amount of Na+ resulted in a monotonous decrease in R, but its further addition restored a remarkable increase in R similar to the critical behaviors in the salt-free system. In the case of off-critical sample, the addition of either Ca2+ or Na+ above a certain concentration induced a change in R from a monotonous decrease to a remarkable increase. For both critical and off-critical concentrations of alpha-elastin, Ca2+ and Na+ brought about an elevation and a lowering of the temperature at which the sample started to be turbid, respectively.
进行了准弹性光散射研究，以探究金属阳离子（如Ca2+和Na+）对α-弹性蛋白凝聚过程早期阶段的影响。α-弹性蛋白是一种源自生物弹性蛋白的化学裂解产物，实验在水溶液中进行。特别地，我们的注意力集中在早期工作中发现的两种动力学行为的变化上，即对于α-弹性蛋白的临界浓度和非临界浓度，分子的流体动力学半径R分别随温度显著增加和单调减小。对于临界α-弹性蛋白浓度，发现添加Ca2+对在无Ca2+情况下观察到的R的陡峭温度曲线影响很小。另一方面，添加少量Na+会导致R单调减小，但进一步添加会使R显著增加，恢复到类似于无盐体系中的临界行为。对于非临界样品，添加高于一定浓度的Ca2+或Na+会导致R从单调减小变为显著增加。对于α-弹性蛋白的临界浓度和非临界浓度，Ca2+和Na+分别使样品开始变浑浊的温度升高和降低。
