NMR based Structural Biology, MPI for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany.
Department of Chemistry, Gauhati University, Gopinath Bardoloi Nagar, Guwahati, 781014, India.
Nat Commun. 2020 Sep 1;11(1):4372. doi: 10.1038/s41467-020-18093-5.
3D molecular structure determination is a challenge for organic compounds or natural products available in minute amounts. Proton/proton and proton/carbon correlations yield the constitution. J couplings and NOEs oftentimes supported by one-bond H,C residual dipolar couplings (RDCs) or by C residual chemical shift anisotropies (RCSAs) provide the relative configuration. However, these RDCs or carbon RCSAs rely on 1% natural abundance of C preventing their use for compounds available only in quantities of a few 10's of µgs. By contrast, H RCSAs provide similar information on spatial orientation of structural moieties within a molecule, while using the abundant H spin. Herein, H RCSAs are accurately measured using constrained aligning gels or liquid crystals and applied to the 3D structural determination of molecules with varying complexities. Even more, deuterated alignment media allow the elucidation of the relative configuration of around 35 µg of a briarane compound isolated from Briareum asbestinum.
3D 分子结构测定对于可用数量极少的有机化合物或天然产物来说是一项挑战。质子/质子和质子/碳相关可以确定其组成。通过单键氢、碳残基偶极耦合(RDC)或碳残基化学位移各向异性(RCSA)支持的 J 偶合和 NOE 通常提供相对构型。然而,这些 RDC 或碳 RCSA 依赖于 1%的 C 天然丰度,这使得它们无法用于仅可获得几十个微克的化合物。相比之下,H RCSA 提供了关于分子内结构部分空间取向的类似信息,同时使用丰富的 H 自旋。本文中,通过约束排列凝胶或液晶准确测量 H RCSA,并将其应用于具有不同复杂程度的分子的 3D 结构测定。更重要的是,氘代排列介质允许阐明从 Briareum asbestinum 中分离出的约 35μg 布里亚烷化合物的相对构型。