作者:Pedro Hidalgo-Fernández、Eva Ayet、Ivan Canal、Joan-Antoni Farrera
DOI:10.1039/b605081f
日期:——
Glycoluril derivatives with a carboxylic acid side chain have been synthesized and shown to bind to both avidin and streptavidin. Introduction of a valerate side chain in glycoluril led to an increased binding to both proteins only when the valerate group was bound to a N atom and with the proper stereochemistry [(+)-enantiomer]. On the other hand, introduction of the valerate side chain either on the bridgehead carbon or on the N atom with the opposite stereochemistry [(−)-enantiomer] led to a decrease in binding constant compared with unsubstituted glycoluril. Direct spectrophotometric competitive titration of each protein with a racemic ligand allowed measurement of the enantioselectivity of the ligand–protein complexation, together with the binding constant of the two enantiomers. In the case of the N-substituted glycoluril, the extension of the side chain by one methylene group, from valerate to caproate, led to an increase in the binding constant to both proteins. Docking studies using AutoDock 3.05 have been performed in order to predict the binding modes of these ligands to streptavidin. The effect of the stereochemistry and the position of the side chain on the binding constant to streptavidin is discussed in view of the predicted binding modes.
我们合成了带有羧酸侧链的甘氨酰脲衍生物,并证明它们能与阿维蛋白和链霉亲和素结合。只有当戊酸基团与 N 原子结合并具有适当的立体化学结构[(+)-对映体]时,在甘氨酰脲中引入戊酸侧链才会增加与这两种蛋白质的结合力。另一方面,与未取代的甘草利相比,在桥头碳或具有相反立体化学结构的 N 原子上引入戊酸侧链[(-)-对映体]会导致结合常数下降。将每种蛋白质与外消旋配体进行直接分光光度竞争滴定,可以测量配体与蛋白质复配的对映体选择性以及两种对映体的结合常数。就 N-取代的甘氨酰脲而言,侧链延伸一个亚甲基(从戊酸酯到己酸酯)后,与两种蛋白质的结合常数都增加了。为了预测这些配体与链霉亲和素的结合模式,我们使用 AutoDock 3.05 进行了对接研究。根据预测的结合模式,讨论了立体化学和侧链位置对链霉亲和素结合常数的影响。