Mehta Chirag M, White Edward T, Litster James D
Advanced Water Management Center, The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia.
Biotechnol Prog. 2013 Sep-Oct;29(5):1203-11. doi: 10.1002/btpr.1760. Epub 2013 Jun 27.
Interactions measurement is a valuable tool to predict equilibrium phase separation of a desired protein in the presence of unwanted macromolecules. In this study, cross-interactions were measured as the osmotic second virial cross-coefficients (B23 ) for the three binary protein systems involving lysozyme, ovalbumin, and α-amylase in salt solutions (sodium chloride and ammonium sulfate). They were correlated with solubility for the binary protein mixtures. The cross-interaction behavior at different salt concentrations was interpreted by either electrostatic or hydrophobic interaction forces. At low salt concentrations, the protein surface charge dominates cross-interaction behavior as a function of pH. With added ovalbumin, the lysozyme solubility decreased linearly at low salt concentration in sodium chloride and increased at high salt concentration in ammonium sulfate. The B23 value was found to be proportional to the slope of the lysozyme solubility against ovalbumin concentration and the correlation was explained by preferential interaction theory.
相互作用测量是预测在存在不需要的大分子时所需蛋白质平衡相分离的一种有价值的工具。在本研究中，交叉相互作用被测量为盐溶液（氯化钠和硫酸铵）中涉及溶菌酶、卵清蛋白和α-淀粉酶的三种二元蛋白质系统的渗透第二维里交叉系数（B23）。它们与二元蛋白质混合物的溶解度相关。不同盐浓度下的交叉相互作用行为通过静电或疏水相互作用力来解释。在低盐浓度下，蛋白质表面电荷作为pH的函数主导交叉相互作用行为。添加卵清蛋白后，在氯化钠中的低盐浓度下溶菌酶溶解度线性降低，而在硫酸铵中的高盐浓度下溶菌酶溶解度增加。发现B23值与溶菌酶溶解度相对于卵清蛋白浓度的斜率成正比，并且这种相关性由优先相互作用理论解释。
