Kinetics of ligand binding to receptor immobilized in a polymer matrix, as detected with an evanescent wave biosensor .1. A computer simulation of the influence of mass transport
Kinetics of ligand binding to receptor immobilized in a polymer matrix, as detected with an evanescent wave biosensor .1. A computer simulation of the influence of mass transport
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DOI：
10.1016/s0006-3495(96)79681-9
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发表时间：
1996-03-01
影响因子：
3.4
通讯作者：
Schuck, P
中科院分区：
文献类型：
--
作者：
Schuck, P
研究了用倏逝波生物传感器检测的质量传递对聚合物基质中固定受体与配体结合的影响。采用一维计算机模型研究了配体溶液与聚合物凝胶之间以及凝胶内部的质量传递，研究了不同条件下扩散系数、配分系数、基质厚度和固定化受体分布对配体与聚合物凝胶之间质量传递的影响。在可能适用于许多已发表的实验研究的条件下，发现基质内的扩散显著降低了整体配体运输。对于相对缓慢的反应，凝胶中自由配体和结合配体的空间梯度较小，而对于相对快速的反应，在平衡建立之前，凝胶内配体的不均匀性很强。描述了与已发表的实验数据相似的几种偏离理想的伪一阶结合过程曲线的类型。在某些情况下，极端输运受限的反应可以符合明显理想的结合过程曲线，尽管其表观反应速率远低于真实反应速率。然而，表观速率常数的比值可以半定量地与真实平衡常数相一致。显然，在高受体饱和度下，高化学反应速率可导致“协同”结合。在存在输运限制的情况下，解离可以用单指数或双指数很好地描述，其表观速率常数大大低于内在化学速率常数。凝胶中的输运限制可以将许多通常未知的因素引入到结合过程曲线中。模拟表明，与理想结合过程曲线的意外偏差可能是由于高度输运影响的结合动力学。使用较薄的聚合物基质可以显著增加可检测速率常数的范围。
The influence of mass transport on ligand binding to receptor immobilized in a polymer matrix, as detected with an evanescent wave biosensor, was investigated. A one-dimensional computer model for the mass transport of ligand between the bulk solution and the polymer gel and within the gel was employed, and the influence of the diffusion coefficient, the partition coefficient, the thickness of the matrix, and the distribution of immobilized receptor were studied for a variety of conditions. Under conditions that may apply to many published experimental studies, diffusion within the matrix was found to decrease the overall ligand transport significantly. For relatively slow reactions, small spatial gradients of free and bound ligand in the gel are found, whereas for relatively rapid reactions strong inhomogeneities of ligand within the gel occur before establishment of equilibrium. Several types of deviations from ideal pseudo-first-order binding progress curves are described that resemble those of published experimental data. Extremely transport limited reactions can in some cases be fitted with apparently ideal binding progress curves, although with apparent reaction rates that are much lower than the true reaction rates. Nevertheless, the ratio of the apparent rate constants can be semiquantitatively consistent with the true equilibrium constant. Apparently ''cooperative'' binding can result from high chemical on rates at high receptor saturation. Dissociation in the presence of transport limitation was found to be well described empirically by a single or a double exponential, with both apparent rate constants considerably lower than the intrinsic chemical rate constant, Transport limitations in the gel can introduce many generally unknown factors into the binding progress curve. The simulations suggest that unexpected deviations from ideal binding progress curves may be due to highly transport influenced binding kinetics. The use of a thinner polymer matrix could significantly increase the range of detectable rate constants.