Molecular modeling on solvent effect and interaction mechanism of fentanyl analogs to mu-opioid receptor.
AIM
To do theoretical study about solvation effect and interaction mechanism of fentanyl analogs (FA) to mu opioid receptor (microOR).


METHODS
Flexible docking (FlexiDock) was performed by using the possible active conformations of FA and optimized 3D structure of mu opioid receptor. Binding energies were calculated. Comparative molecular force field analysis (CoMFA) and quantitative structure activity relationship (QSAR) studies were carried out based on results of flexible docking. Solvation effects were considered by studying interaction of FA with water molecules. Partial least square (PLS) analysis was used to calculate regression equation for analgesic activities using binding energies as descriptive factor.


RESULTS
1) Binding conformations of these analogs derived by flexible docking were reasonable. 2) It was most possible for the FA to exist in water solution in the form of binding conformations. 3) Energetic calculation and QSAR analysis showed a good correlation between the calculated binding energies of FA and their analgesic activities. 4) Based on the 3D-model, the possible interaction mechanism of FA with mu opioid receptor can be illustrated reasonably.


CONCLUSION
The nature of the correlation between the binding affinities and analgesic activities of FA was explained by our modeling result.