Harinarayan C, Mueller J, Ljunglöf A, Fahrner R, Van Alstine J, van Reis R
Genentech Inc., South San Francisco, California, USA.
Biotechnol Bioeng. 2006 Dec 5;95(5):775-87. doi: 10.1002/bit.21080.
Protein dynamic binding capacities on ion exchange resins are typically expected to decrease with increasing conductivity and decreasing protein charge. There are, however, conditions where capacity increases with increasing conductivity and decreasing protein charge. Capacity measurements on two different commercial ion exchange resins with three different monoclonal antibodies at various pH and conductivities exhibited two domains. In the first domain, the capacity unexpectedly increased with increasing conductivity and decreasing protein charge. The second domain exhibited traditional behavior. A mechanism to explain the first domain is postulated; proteins initially bind to the outer pore regions and electrostatically hinder subsequent protein transport. Such a mechanism is supported by protein capacity and confocal microscopy studies whose results suggest how knowledge of the two types of IEX behavior can be leveraged in optimizing resins and processes.
离子交换树脂上蛋白质的动态结合能力通常预计会随着电导率的增加和蛋白质电荷的减少而降低。然而，在某些条件下，结合能力会随着电导率的增加和蛋白质电荷的减少而增加。在不同pH值和电导率下，使用三种不同的单克隆抗体对两种不同的商业离子交换树脂进行的结合能力测量显示出两个区域。在第一个区域中，结合能力出乎意料地随着电导率的增加和蛋白质电荷的减少而增加。第二个区域表现出传统行为。本文提出了一种解释第一个区域的机制；蛋白质最初结合到外孔区域，并在静电作用下阻碍后续蛋白质的运输。蛋白质结合能力和共聚焦显微镜研究支持了这种机制，其结果表明如何利用这两种离子交换行为的知识来优化树脂和工艺。
