The gramicidin A channel The energy profile calculated for Na+ in the presence of water with inclusion of the flexibility of the ethanolamine tail

AbstractThe effect of the conformational freedom of the ethanolamine tail of gramicidin A on the energy profile for the transfer of Na+, computed in the presence of water, shows an appreciable lowering of the minimum at 10.5 Å, and a splitting of the entrance barrier. The deep energy region at the channel mouth remains, however, the deepest one and contains a site of strong interaction of the ion with the Trp 11 carbonyl, at about 12 Å from the center