Díaz Natalia, Suárez Dimas, Sordo Tomás L
Departamento de Química Física y Analítica, Universidad de Oviedo, C/Julián Clavería 8, 33006; Oviedo, Spain.
J Comput Chem. 2003 Nov 30;24(15):1864-73. doi: 10.1002/jcc.10350.
Herein, we present theoretical results on the conformational properties of benzylpenicillin, which are characterized by means of quantum chemical calculations (MP2/6-31G* and B3LYP/6-31G*) and classical molecular dynamics simulations (5 ns) both in the gas phase and in aqueous solution. In the gas phase, the benzylpenicillin conformer in which the thiazolidine ring has the carboxylate group oriented axially is the most favored one. Both intramolecular CH. O and dispersion interactions contribute to stabilize the axial conformer with respect to the equatorial one. In aqueous solution, a molecular dynamics simulation predicts a relative population of the axial:equatorial conformers of 0.70:0.30 in consonance with NMR experimental data. Overall, the quantum chemical calculations as well as the simulations give insight into substituent effects, the conformational dynamics of benzylpenicillin, the frequency of ring-puckering motions, and the correlation of side chain and ring-puckering motions.
在此，我们展示了关于苄青霉素构象性质的理论结果，这些结果通过量子化学计算（MP2/6 - 31G和B3LYP/6 - 31G）以及在气相和水溶液中的经典分子动力学模拟（5纳秒）来表征。在气相中，噻唑烷环上羧基轴向取向的苄青霉素构象异构体是最有利的。分子内的CH…O和色散相互作用都有助于使轴向构象异构体相对于赤道构象异构体更稳定。在水溶液中，分子动力学模拟预测轴向：赤道构象异构体的相对丰度为0.70:0.30，这与核磁共振实验数据一致。总体而言，量子化学计算以及模拟为取代基效应、苄青霉素的构象动力学、环扭曲运动的频率以及侧链与环扭曲运动的相关性提供了深入了解。
