Preliminary Study Of The ABEEM/MM Force Field For Neutral Phospholipid Molecules

Phospholipid molecules are the basic framework of cell membranes,and play an important role in many life activities.Since both inside and outside of the cell membrane are aqueous solutions,studies on the interactions between phospholipid and water are also of great significance.Based on the previous research of our group,we continue to establish the ABEEM/MM fluctuating charge force field for phospholipid molecules,and to study more neutral phospholipid molecules,including DPPC,DMPC,POPC,DLPC,DOPC,DOPE and POPE.According to the QM results,we re-fitted and optimized the relevant parameters,and extended it to phospholipid-water system,considered the interactions between the hydrophobic tail of the phospholipid and water molecules.The constructed ABEEM/MM force field herein was applied into investigations on the structures and properties of PC phospholipid molecules,including DPPC,POPC,DMPC,DOPC and DLPC.The results from the ABEEM/MM are in good agreement with the QM results,and the average absolute deviations(AADs)of the bond lengths,bond angles,dihedral angles are less than 0.011?,1.09o and 2.87o,respectively;the linear correlation coefficients of charge distribution are all above 0.98.For the phospholipid-water system,compared with the QM results,the AADs of the hydrogen bond lengths and hydrogen bond angles are 0.136? and 3.07o,respectively;the linear correlation coefficients of the charge distributions are all above 0.98,and the binding energies are in consistent with the QM results.For the PE phospholipid molecules,including POPE and DOPE,compared with the QM results,the AADs of the bond lengths,bond angles and dihedral angles are less than 0.009?,0.93o,1.67o,respectively;the linear correlation coefficients of the charge distributions are all above 0.98.For the PE-water system,the AADs of hydrogen bond lengths and hydrogen bond angles are 0.133? and 9.66o,respectively;the linear correlation coefficients of the charge distributions are all above 0.98,and the binding energies are also in agreement with the QM results.In general,the ABEEM/MM for the phospholipid molecule constructed in this thesis can represent the structures and properties of the phospholipid molecules concerned,and this may serve as an important reference for further study on membrane proteins using the ABEEM/MM.