Palumaa P, Järv J
Biochim Biophys Acta. 1984 Jan 18;784(1):35-9. doi: 10.1016/0167-4838(84)90169-9.
The kinetics of acetylcholinesterase alkylation with N,N-dimethyl-2-phenylaziridinium ion, the anionic-site-directed affinity label, has been investigated in the presence of alkylboronic acids, which are known as the esteratic-site-directed reversible inhibitors of the enzyme. The ternary complex of the enzyme, the aziridinium ion and alkylboronic acid, are formed in this reaction. In the case of propylboronic acid, for which the complete kinetic analysis of the acceleration effect has been carried out, the 85-fold increase in the rate of the enzyme alkylation reaction has been found. This acceleration effect was connected with the alkylation step, whereas the non-covalent binding of the aziridinium ion in the enzyme active centre was even hindered by the alkylboronic acid. The possible mechanism of this kinetic acceleration phenomenon is discussed with special reference to the kinetic data for the spontaneous solvolysis reaction of the aziridinium ion in water and organic solvents.
在烷基硼酸存在的情况下，研究了乙酰胆碱酯酶与N，N - 二甲基 - 2 - 苯基氮丙啶离子（一种阴离子位点导向的亲和标记物）的烷基化动力学，烷基硼酸是已知的该酶的酯解位点导向的可逆抑制剂。在该反应中形成了酶、氮丙啶离子和烷基硼酸的三元复合物。对于已对加速效应进行完整动力学分析的丙基硼酸，发现酶烷基化反应速率增加了85倍。这种加速效应与烷基化步骤有关，而氮丙啶离子在酶活性中心的非共价结合甚至受到烷基硼酸的阻碍。结合氮丙啶离子在水和有机溶剂中的自发溶剂解反应的动力学数据，讨论了这种动力学加速现象的可能机制。
