Materials Processing Center, Department of Physics, and Center for Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Proc Natl Acad Sci U S A. 2010 Jul 27;107(30):13282-7. doi: 10.1073/pnas.1008353107. Epub 2010 Jul 7.
We have experimentally determined the coexistence surface characterizing the phase behavior of gammaD-betaB1-water ternary solutions. The coexistence surface fully describes the solution conditions, i.e., temperature, protein concentration, and protein composition, at which liquid-liquid phase separation occurs in a ternary solution. We have observed a significant demixing of gammaD and betaB1 i.e., large difference of composition in the two coexisting phases. This demixing suggests that the energy of the gammaD-betaB1 attractive interaction is significantly smaller than the energy of the gammaD-gammaD attractive interaction. We also observed the lowering of the phase separation temperature upon increasing of the fraction of betaB1 in solution. We provide a theoretical analysis of our experimental data, which enables a quantitative description of our principal experimental findings. In this way, we have evaluated the magnitude and temperature dependence of the relevant interprotein interaction energies. Our findings provide insight into the factors essential for maintaining lens proteins in a single homogeneous phase, thereby enabling lens transparency.
我们通过实验确定了描述γD-βB1-水三元溶液相行为的共存表面。该共存表面完整描述了溶液条件，即温度、蛋白质浓度和蛋白质组成，在这些条件下，三元溶液中会发生液-液相分离。我们观察到γD 和βB1 的显著分相，即两个共存相之间的组成存在较大差异。这种分相表明，γD-βB1 吸引力相互作用的能量明显小于γD-γD 吸引力相互作用的能量。我们还观察到，随着溶液中βB1 分数的增加，相分离温度降低。我们对实验数据进行了理论分析，这使得我们能够对主要的实验发现进行定量描述。通过这种方式，我们评估了相关蛋白质间相互作用能量的大小和温度依赖性。我们的研究结果深入了解了维持晶状体蛋白质处于单一均相的关键因素，从而使晶状体保持透明。
