三种低聚肽的物理化学性质的密度泛函研究

运用密度泛函理论对三种由不同氨基酸组成的低聚肽进行结构优化，并对其平均结合能和振动红外光谱进行分析，三种低聚肽分别为甘氨酸低聚肽、甘-丙氨酸低聚肽和甘-色氨酸低聚肽.本文主要研究，在肽链骨架相同而侧链基团不同的情况下，低聚肽的物理化学性质变化.结果表明，随着氨基酸残基数量的增加，三种低聚肽的结构稳定性都会增强，同时三种低聚肽也存在着尺寸效应，即官能团的振动都存在红移和奇偶振荡现象.侧链基团的引入会对低聚肽骨架的几何结构产生影响，在肽链生长过程中，侧链基团空间位阻大的分子优先自组装.本研究对应用红外光谱测定肽链基团和合成低聚肽等方面有一定指导意义.

DFT research on properties of physics and chemistry of three kinds of oligopeptides

This paper reports the research mainly on the physical and chemical properties of oligopeptides with same backbone and different side groups. By using the density functional theory, a study on three kinds of oligopeptides made from different amino acids is given. The three kinds of oligopeptides are: glycine linear oligopeptide, oligopeptide made from glycine and alanine, and oligopeptide made from glycine and tryptophan. Geometric structures, average binding energies and vibration frequencies of the oligopeptides are examined. The results show that with the increasing number of residues, the stability of oligopeptides is enhanced. The vibration infrared spectrum analyses show that with the growth of oligopeptides, the typical functional groups show the trend of red shift and even-odd shift. The introduction of side chain groups will affect the geometrical structure of oligopeptides backbone, and the amino acid with bigger side group tends to be self-assembly early in the growth process. The result is significant to measure the length and number of residue of peptide chain.