N-乙酰基-L-赖氨酸-甲酰胺侧链构象的理论分析

Theoretical Conformational Analysis of the Side Chain in Methylamide of N-acetyl-L-lysine

目的分析N-乙酰基-L-赖氨酸-甲酰胺的非键和静电相互作用、拓朴能、键角的弯曲和氢键,研究它们的空间结构。方法当主链的最大构象可能性确定时,侧链的键角和两面角φ,ψ在每一点变化的情况下,用能量低化的方法得到了构象图,并评价了主链和侧链的空间的相互制约性。当主链为低能式而侧链具有最大拓朴势时,φ,ψ,χ_1-χ_5角的所有组合作为初始近似的情况下,计算了分子的优势构象.结果N-乙酰基-L-赖氨酸-甲酰胺的稳定构象与赖氨酸残基在蛋白质中的已知结构的几何构型相符合.结论赖氨酸残基在蛋白质中构象即为赖氨酸孤立单肽的优势构象。

Objective The spatial structure of methylamide of N - acetyl - L - lysine has been analysed by taking into account non -bonded and electrostatic interactions, torsional energy, bond angles distortion and hydrogen bonding. Methods Conformational capacities of the backbone and mutual dependence of spatial structures of the backbone and the side chain were described by conformational maps obtained by energy minimisation, the dihedral angles and the bond angles of the side chain being varied for every φ ,ψpoint. Results Every possible conformation for φ, ψ ,x1 - x5 - angles was used corresponding to the stable form of the backbone and to torsion potential minima of the initial approximations in the calculation of preferred conformations of the molecular. Conformations were made between stable forms of the methylamide of N - acety - L - lysine and Lys residues in proteins with known structure. Conclusions The conformation of lysine in proteins is the same as the stable conformation of lysine in the monopeptide.