[On the methods of calculation of the electrostatic potential in a protein channel].

The profiles of the electrostatic potential along the axis of a gramicidin channel were calculated using two quantum chemistry methods (EHT and CNDO/2) and three methods of force fields (AMBER, CHARMM, and OPLS). The calculations were performed without taking into account the contribution of water. A comparative analysis of the calculated profiles indicated that the electrostatic field of point charges of the CHARMM force field is close to that obtained by the quantum chemistry methods. It was concluded that there is no need to calculate the electric field using laborious quantum-mechanical methods since the less laborious method of the CHARMM force field gives approximately the same results.