Aggregation, hydrogen bonding and thermodynamic studies on Boc-Val-Val-Ile-OMe tripeptide micelles in chloroform
作者:R. Jayakumar、R. G. Jeevan、A. B. Mandal、P. T. Manoharan
DOI:10.1039/ft9949002725
日期:——
Evidence for micelle formation of Boc-Val-Val-Ile-OMe (Boc =tert-butyloxycarbonyl) tripeptide (1), in chloroform has been obtained from IR and Raman scatter fluorescence spectroscopies. The critical micelle concentrations (c.m.c.s) of this peptide, obtained by these techniques, correlate well. It has been found that the micelle formation of the peptide in chloroform is hindered by increasing temperature. The aggregation numbers of the peptide have also been determined to be almost independent of temperature. The ΔmG⊖, ΔmH⊖, ΔmS⊖ and ΔmCp values have been estimated. Results from the above thermodynamic parameters indicate that the driving force for micellization of the tripeptide 1 in chloroform is entirely enthalpic in nature and the aggregates of the peptide in chloroform are ordered. The IR spectra of the peptide in the pre- and post-micellar regions were analysed; there is no change in the intensity of the intermolecular hydrogen-bonding pattern for the peptide in the monomeric and micellar states. However, the intensity of the solvent-exposed —N—H stretching band increased as a function of peptide concentration after attaining c.m.c.
从红外和拉曼散射荧光光谱中获得了氯仿中 Boc-Val-Val-Ile-OMe(Boc = 叔丁氧羰基)三肽 (1) 胶束形成的证据。通过这些技术获得的该肽的临界胶束浓度 (c.m.c.s) 具有良好的相关性。已经发现,升高温度会阻碍肽在氯仿中的胶束形成。还确定肽的聚集数几乎与温度无关。已估计 ΔmG⊖、ΔmH⊖、ΔmS⊖ 和 ΔmCp 值。上述热力学参数的结果表明,三肽1在氯仿中胶束化的驱动力本质上是完全焓的,并且肽在氯仿中的聚集体是有序的。分析了胶束前和胶束后区域肽的红外光谱;单体和胶束状态下的肽的分子间氢键模式的强度没有变化。然而,在达到 c.m.c. 后,暴露于溶剂的 -NH 伸缩带的强度作为肽浓度的函数而增加。