关键词: 甲硫氨酸-脑啡肽, 分子动力学模拟, 药效团, 构象分析

Abstract:

The conformational properties of Met-enkephalin (Tyr-Gly-Gly-Phe-Met) were investigated by high temperature quenched molecular dynamics simulations in vapor. Each of these selected structures were then analyzed according to their backbone(φ,Ψ) conformational distributions and sorted into 13 families by computing the rms difference between the Cα-C backbone fragments of each residue over all the structures. Selected lowest energy conformations from each of 13 families were thoroughly energy minimized. The results of simulations show that Met-enkephalin is a flexible molecule. It shows a type Ⅰβ-turn, with the Gly2 carbonyl forming a hydrogen bond with the Met5 amino proton and a type Ⅱβ turn, with the Tyr1 amino proton forming a hydrogen bond with the Phe4 carbonyl. The multiple fit were carried out for all of the 13 conformers with morphine(9 atoms on the pharmacophore groups). F2 and F6 were the most similar to morphine. The rms were 0.0504 nm and 0.0726 nm. The results of simulations also show that Tyr amino N corresponds to N on piperidine ring in morphine, Tyr phenol corresponds to the phenol in morphine, the aromatic ring of Phe corresponds to the cyclohexene ring in morphine. The distances between the three pharmacophores, d1 (Tyr N to Tyr OH), d2 (Tyr N to Tyr du1), d3(Tyr N to Phe du2) and d4(Tyr N to Phe du2) were found to be about 0.8, 0.5, 0.7-0.9 and 0.5 nm, respectively, the corresponding, distances of morphine were found to be 0.7697(N18 to O6),0.5143(N18 to du25), 0.3962(N18 to du24)和0.5566(N18 to O15)nm. Therefore, they may be acted on the same receptor. This model should aid in pharmaceutical design of peptide and nonpeptide ligands with opioid.

Key words: Met-enkephalin, Molecular dynamics simulation, Pharmacophore, Conformational families