磷脂分子DPPC的浮动电荷分子力场

The fluctuating charge force filed of a phospholipid molecule(DPPC)

基于量子化学(QM)计算和原子-键电负性均衡浮动电荷分子力场(ABEEMσπ/MM),构建了1,2-二棕榈酰磷脂酰胆碱(1,2-dipalmitoyl-sn-phosphatidylcholine,DPPC)分子的可极化势能函数.首先将DPPC分子分成乙基三甲基铵(ETMA)、乙酸甲酯(MAS)、磷酸二甲酯(DMP)和烷烃等官能团模型小分子片段,依据这些模型分子的QM结果,优选并确定相关电荷参数及力场参数.应用ABEEMσπ/MM对模型小分子的计算结果与QM计算结果符合很好,其中,稳定结构的键长、键角、二面角的绝对平均偏差(AAD)分别为0.000 5nm、1.59°和1.33°,两者的电荷分布的线性相关系数为0.968 8.进一步将上述函数应用到研究DPPC分子的结构和电荷分布,并与QM结果相比,结果表明:键长、键角、二面角的AAD和均方根偏差(RMSD)分别仅为0.000 01和0.000 02nm、0.006°和0.009°、0.007°和0.011°;两者计算得到的电荷分布的线性相关系数为0.965 9.

Based on the quantum chemical(QM)calculations and the atom-bond electronegativity equalization fluctuating charge force field(ABEEMσπ/MM),a polarizable potential energy function of Sn-1,2-dipalmitoyl-phosphatidylcholine(DPPC)was constructed.First,the DPPC molecule was divided into fragments of model functional groups,including ethyltrimethylammonium(ETMA),methyl acetate(MAS),dimethyl phosphate(DMP)and alkanes.Based on the QM result of these model molecules,the charge parameters and force field parameters were optimized and determined.The results of these model molecules from ABEEMσπ/MM are in good agreement with those of QM,and the average absolute deviation(AAD)of the bond lengths,bond angles and dihedral angles of the stable structures are0.0005nm,1.59°and1.33°,respectively.The linear correlation coefficient of the charge distribution between ABEEMσπ/MM and QM is0.9688.Then the parameters were applied to study the structure and charge distribution of DPPC.Compared with the QM results,the AADs,root mean square deviations(RMSDs)of the bond lengths,bond angles and dihedral angles are only0.00001and0.00002nm,0.006°and0.009°,0.007°and0.011°,respectively.The linear correlation coefficient of the charge distribution between ABEEMσπ/MM and QM is0.9659.