具有 β 转角偏向序列的催化肽二级结构的多样性,Journal of the American Chemical Society

当前位置： X-MOL 学术 › J. Am. Chem. Soc. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

具有 β 转角偏向序列的催化肽二级结构的多样性
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2016-12-28 , DOI: 10.1021/jacs.6b11348
Anthony J Metrano ₁ , Nadia C Abascal ₁ , Brandon Q Mercado ₁ , Eric K Paulson ₁ , Anna E Hurtley ₁ , Scott J Miller ₁

Affiliation

X 射线晶体学已应用于一系列四肽的结构分析，这些四肽之前已评估了其在间质选择性溴化反应中的催化活性。该系列的共同点是中央 Pro-Xaa 序列，其中 Pro 是 l-或 d-脯氨酸，选择它是为了有利于规范 β 转角二级结构的成核。对 35 种不同肽序列的晶体学分析揭示了一系列构象状态。观察到的差异不仅出现在 Pro-Xaa 环区发生改变的情况下，而且还出现在对侧翼残基进行看似微妙的改变时。在许多情况下，观察到相同序列的不同构象异构体，或者作为同一晶胞内的对称独立分子，或者作为多晶型物。使用 DFT 的计算研究为固态结构特征的分析提供了额外的见解。将选定的 X 射线晶体结构与从测量的质子化学位移、3J 值和 1H–1H-NOESY 接触得出的相应溶液结构进行比较。这些发现意味着，简单的基于肽的催化剂可用的构象空间比先例所暗示的更加多样化。对该家族肽的多个基态构象的直接观察，以及与构象平衡相关的动态过程，不仅强调了设计基于肽的催化剂的挑战，而且强调了预测其可接近的过渡态的困难。这些发现暗示了基于肽的催化剂的构象之间的低势垒相互转化对于多步骤、对映选择性反应的优势。

"点击查看英文标题和摘要"

Diversity of Secondary Structure in Catalytic Peptides with β-Turn-Biased Sequences

X-ray crystallography has been applied to the structural analysis of a series of tetrapeptides that were previously assessed for catalytic activity in an atroposelective bromination reaction. Common to the series is a central Pro-Xaa sequence, where Pro is either l- or d-proline, which was chosen to favor nucleation of canonical β-turn secondary structures. Crystallographic analysis of 35 different peptide sequences revealed a range of conformational states. The observed differences appear not only in cases where the Pro-Xaa loop-region is altered, but also when seemingly subtle alterations to the flanking residues are introduced. In many instances, distinct conformers of the same sequence were observed, either as symmetry-independent molecules within the same unit cell or as polymorphs. Computational studies using DFT provided additional insight into the analysis of solid-state structural features. Select X-ray crystal structures were compared to the corresponding solution structures derived from measured proton chemical shifts, 3J-values, and 1H–1H-NOESY contacts. These findings imply that the conformational space available to simple peptide-based catalysts is more diverse than precedent might suggest. The direct observation of multiple ground state conformations for peptides of this family, as well as the dynamic processes associated with conformational equilibria, underscore not only the challenge of designing peptide-based catalysts, but also the difficulty in predicting their accessible transition states. These findings implicate the advantages of low-barrier interconversions between conformations of peptide-based catalysts for multistep, enantioselective reactions.

更新日期：2016-12-28

点击分享查看原文

点击收藏

公开下载

阅读更多本刊新发论文本刊介绍/投稿指南