Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
J Am Chem Soc. 2012 Mar 21;134(11):5032-5. doi: 10.1021/ja2114135. Epub 2012 Mar 7.
The peptide amide-I vibration of a proline turn encodes information on the turn structure. In this study, FTIR, two-dimensional IR spectroscopy and molecular dynamics simulations were employed to characterize the varying turn conformations that exist in the GVGX(L)PGVG family of disordered peptides. This analysis revealed that changing the size of the side chain at the X amino acid site from Gly to Ala to Val substantially alters the conformation of the peptide. To quantify this effect, proline peak shifts and intensity changes were compared to a structure-based spectroscopic model. These simulated spectra were used to assign the population of type-II β turns, bulged turns, and irregular β turns for each peptide. Of particular interest was the Val variant commonly found in the protein elastin, which contained a 25% population of irregular β turns containing two peptide hydrogen bonds to the proline C═O.
脯氨酸环的酰胺 I 振动可以编码有关环结构的信息。在这项研究中，我们使用傅里叶变换红外光谱、二维红外光谱和分子动力学模拟来描述 GVGX（L）PGVG 家族无规多肽中存在的变化的环构象。这项分析表明，改变 X 氨基酸位置的侧链大小，从甘氨酸到丙氨酸再到缬氨酸，会极大地改变肽的构象。为了量化这种影响，将脯氨酸峰的位移和强度变化与基于结构的光谱模型进行了比较。这些模拟光谱用于为每种肽分配 II 型β 转角、凸起环和不规则β转角的比例。特别值得关注的是弹性蛋白中常见的缬氨酸变体，它含有 25%的不规则β转角，其中两个肽氢键与脯氨酸的 C═O 相连。
