Analysis of allosterism in functional assays
Analysis of allosterism in functional assays
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DOI：
10.1124/jpet.105.090886
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发表时间：
2005-11-01
影响因子：
3.5
通讯作者：
Ehlert, FJ
中科院分区：
文献类型：
--
作者：
Ehlert, FJ
描述了分析变构调节剂对激动剂反应影响的理论基础。变构调节剂对激动剂的浓度-反应曲线的影响可以归因于观察到的解离常数和激动剂-受体复合体的内在效力的变化。这两个变化都可以用一个系数或系数来表示。可以估计激动剂效力的改变系数除以激动剂解离常数的比率。这一比率被指定为激动剂在变构调节剂存在时的相对活性(RA)。对于每个浓度的变构调节剂，无论浓度-反应曲线的形状如何，都可以通过非线性回归分析来估计其RA值。将RA值与变构调节剂的浓度进行回归分析，得到了变构调节剂的解离常数(KA)和最大RA值。如果对激动剂的浓度-反应曲线服从Logistic函数，并且变构调节剂影响最大反应，则有可能区分亲和力的最大变化和药效的变化。如果激动剂的浓度-反应曲线服从Hill斜率为1的Logistic方程，则可以根据激动剂的EC50和E-max值很容易地估计RA值。这一分析说明了RA值在量化变构效应中的作用。
The theoretical basis for analyzing the effects of an allosteric modulator on the response to an agonist is described. The effects of an allosteric modulator on the concentration-response curve to an agonist can be attributed to changes in the observed dissociation constant and intrinsic efficacy of the agonist-receptor complex. Each of these two changes can be represented by a coefficient or factor. It is possible to estimate the ratio of the coefficient of change in agonist efficacy divided by that for the agonist dissociation constant. This ratio is designated as the relative activity (RA) of the agonist in the presence of the allosteric modulator. The RA value can be estimated for each concentration of allosteric modulator by nonlinear regression analysis, regardless of the shape of the concentration-response curve. Regression analysis of the RA values against the concentration of allosteric modulator yields estimates of the dissociation constant (KA) of the allosteric modulator and the maximal RA value. If the concentration-response curve to the agonist obeys a logistic function and the allosteric modulator influences the maximal response, it is possible to distinguish between the maximal change in affinity from that of efficacy. If the agonist concentration-response curve obeys a logistic equation with a Hill slope of 1, the RA values can be estimated easily from the agonist EC50 and E-max values. This analysis illustrates the utility of the RA value in quantifying allosteric effects.