Chin Wutharath, Compagnon Isabelle, Dognon Jean-Pierre, Canuel Clélia, Piuzzi François, Dimicoli Iliana, von Helden Gert, Meijer Gerard, Mons Michel
Laboratoire Francis Perrin (URA CEA CNRS 2453), Service des Photons, Atomes et Molécules, Centre d'Etudes de Saclay, Bât. 522, 91191 Gif-sur-Yvette Cedex, France.
J Am Chem Soc. 2005 Feb 9;127(5):1388-9. doi: 10.1021/ja042860b.
We report the first gas-phase spectroscopic study of a three-residue model of a peptide chain, Ac-Phe-Gly-Gly-NH2 (Ac = acetyl), using the IR/UV double resonance technique. The existence of at least five different conformers under supersonic expansion conditions is established, most of them exhibiting rather strong intramolecular H-bonds. One of the most populated conformers, however, exhibits a different H-bonding network characterized by two weak H-bonds. Comparison of the amide A and I/II experimental data with density functional theory calculations carried out on a series of selected conformations enables us to assign this conformer to two successive beta-turns along the peptide chain, the two H-bonds being of C10 type, i.e., each of them closing a 10-atom ring in the molecule. The corresponding form is found to be more stable than the 310 helix secondary structure (not observed), presumably because of specific effects due to the glycine residues.
我们报道了使用红外/紫外双共振技术对肽链三残基模型Ac-Phe-Gly-Gly-NH2（Ac = 乙酰基）进行的首次气相光谱研究。在超声速膨胀条件下确定了至少五种不同构象的存在，其中大多数表现出相当强的分子内氢键。然而，最丰富的构象之一表现出不同的氢键网络，其特征是有两个弱氢键。将酰胺A和I/II的实验数据与对一系列选定构象进行的密度泛函理论计算进行比较，使我们能够将该构象沿着肽链指定为两个连续的β-转角，这两个氢键属于C10型，即它们各自在分子中形成一个10原子环。发现相应的形式比310螺旋二级结构（未观察到）更稳定，这可能是由于甘氨酸残基的特定效应。
