Microcalorimetric studies of the interaction mechanisms between proteins and Q-Sepharose at pH near the isoelectric point (pI) -: Effects of NaCl concentration, pH value, and temperature
Microcalorimetric studies of the interaction mechanisms between proteins and Q-Sepharose at pH near the isoelectric point (pI) -: Effects of NaCl concentration, pH value, and temperature
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DOI：
10.1016/s0021-9673(01)00584-2
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发表时间：
2001-04-06
影响因子：
4.1
通讯作者：
Yamamoto, S
中科院分区：
文献类型：
--
作者：
Lin, FY;Chen, CS;Yamamoto, S
本文研究了β-乳球蛋白A和B（Lg A，Lg B）与阴离子交换剂Q-Sepharose在不同NaCl浓度和温度下，通过平衡结合分析和等温滴定量热法直接测定的吸附焓研究了它们在等电点附近的相互作用机理。从Langmuir模型拟合的等温线评价的数据表明，NaCl的加入大大降低了这两种蛋白质与Q-琼脂糖凝胶在pH 5.2的结合亲和力和能力，表明静电力是占主导地位的吸附过程中。然而，在较高的NaCl浓度下，疏水相互作用似乎也参与吸附，吸附曲线证实了这一建议。此外，温度对Lg A或Lg B与Q-Sepharose的平衡结合行为的影响被发现是盐浓度依赖性的，可能是由于它们在0.03 M和0.3 M NaCl下的不同结合机制。其中，在0.3 M NaCl下，疏水相互作用起着更明显的作用。这一推论再次得到吸附理论的支持。所提供的数据提供了进一步的洞察蛋白质和离子交换剂之间的相互作用机制，促进蛋白质分离的优化。(C)出版社：Elsevier Science B. V.
This study examined the interaction mechanisms of beta -lactoglobulins A and B (Lg A, Lg B) with an anion exchanger, Q-Sepharose at pH near the isoelectric point at which the proteins are expected to be electrically neutralized under various NaCl concentrations and temperatures by the equilibrium binding analysis and the adsorption enthalpy directly measured by isothermal titration calorimetry. The data evaluated from isotherms fitted by the Langmuirean model reveal that the addition of NaCl considerably reduced the binding affinities and capacities of both the proteins with Q-Sepharose at pH 5.2, indicating that electrostatic forces are dominant during the adsorption. However, the hydrophobic interaction seems to be involved in adsorption as well at a higher NaCl concentration, and the adsorption enthalpies confirm this suggestion. In addition, the effects of temperature on the equilibrium binding behaviors for Lg A or Lg B with Q-Sepharose were found to be salt concentration-dependent, probably due to their different binding mechanisms at 0.03 M and 0.3 M NaCl. Where, at 0.3 M NaCl, the hydrophobic interaction plays a more pronounced role. This implication was again supported by the adsorption enthalpies. The presented data provide further insight to the interaction mechanisms between proteins and ion exchangers, facilitating the optimization of protein separations. (C) 2001 Published by Elsevier Science B.V.