粉防己碱三维构象的分子动力学模拟

Molecular dynamics simulation of conformations of tetrandrine

[目的]寻找粉防己碱合理的立体构象。[方法]以单分子为体系 ,采用CVFF力场和NVT系统 ,在500K下温度以0 5fs时间步长模拟了粉防己碱50ps的运动轨迹。[结果]分子内形成了相对稳定的三角形的环状结构 ,4个甲氧基在分子的外侧 ,活动相对比较自由。C42和O38代表的一侧分子环运动范围较大 ,而C44和O43代表的另侧运动范围相对较小。四氢异喹啉环本身可以翻转成类似船式或椅式的构象 ,N9所在的环构象变化较大 ,而N18所在的环变化较小。[结论]以势能为指标 ,找到了与最低能量相差5kcal/mol以内的8个构象 。

To find the reasonable cubic conformations of tetrandrine. The molecular dynamics calculations were performed with one molecule in NVT system at fixed temperature(500 K) during 50 ps. The simulation step was 0.5 fs and samples were taken every 10 steps.The distribution of distance of C13_C26、 C42_C44、 C2_C9 and O39_O45 was recorded. The results suggest that there be a triangle cycle in molecule. The methoxyl groups exist in the outside of molecule and rotate freely relatively.The side of C42 and O38 in molecule move within a larger range compared with that of C44 and O38 . The tetrahydroisoquiolines can exchange between boat and chair conformations by themselves. The part with N9 changes more greatly than another part with N18.[Conclusion] Eight conformations were found according to the potential level of within 5 kcal/mol relative to the conformation with lowest energy.