Valente Ana P, Almeida Fábio C L, Nakaie Clovis R, Schreier Shirley, Crusca Edson, Cilli Eduardo M
Department of Medical Biochemistry, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, UFRJ, Rio de Janeiro, Brazil.
J Pept Sci. 2005 Sep;11(9):556-63. doi: 10.1002/psc.659.
The SPPS methodology has continuously been investigated as a valuable model to monitor the solvation properties of polymeric materials. In this connection, the present work applied HRMAS-NMR spectroscopy to examine the dynamics of an aggregating peptide sequence attached to a resin core with varying peptide loading (up to 80%) and solvent system. Low and high substituted BHAR were used for assembling the VQAAIDYING sequence and some of its minor fragments. The HRMAS-NMR results were in agreement with the swelling of each resin, i.e. there was an improved resolution of resonance peaks in the better solvated conditions. Moreover, the peptide loading and the attached peptide sequence also affected the spectra. Strong peptide chain aggregation was observed mainly in highly peptide loaded resins when solvated in CDCl3. Conversely, due to the better swelling of these highly loaded resins in DMSO, improved NMR spectra were acquired in this polar aprotic solvent, thus enabling the detection of relevant sequence-dependent conformational alterations. The more prominent aggregation was displayed by the VQAAIDYING segment and not by any of its intermediary fragments and these findings were also corroborated by EPR studies of these peptide-resins labelled properly with an amino acid-type spin probe.
固相肽合成（SPPS）方法一直被作为监测聚合材料溶剂化性质的一种有价值的模型进行研究。在这方面，本研究应用高分辨魔角旋转核磁共振（HRMAS-NMR）光谱来考察连接在树脂核上的聚集肽序列在不同肽负载量（高达80%）和溶剂体系下的动力学。低取代和高取代的BHAR用于组装VQAAIDYING序列及其一些小片段。HRMAS-NMR结果与每种树脂的溶胀情况一致，即在溶剂化条件较好时，共振峰的分辨率有所提高。此外，肽负载量和连接的肽序列也会影响光谱。当在CDCl3中溶剂化时，主要在高肽负载量的树脂中观察到强烈的肽链聚集。相反，由于这些高负载量的树脂在二甲基亚砜（DMSO）中溶胀较好，因此在这种极性非质子溶剂中获得了更好的NMR光谱，从而能够检测到相关的序列依赖性构象变化。VQAAIDYING片段表现出更明显的聚集，而其任何中间片段都没有，这些发现也得到了用氨基酸型自旋探针正确标记的这些肽树脂的电子顺磁共振（EPR）研究的证实。
