中國科學院武漢物理與數學研究所波譜與原子分子物理國家重點實驗室的楊俊研究組，在發展蛋白質高分辨三維結構的固體核磁共振測定新技術和新方法方面取得重要進展，相關研究結果於近日在《美國化學會》（J. Am. Chem. Soc.）上在線發表。
相對於液體核磁共振和X射線晶體衍射技術，固體核磁共振技術能夠在接近天然環境的條件中來研究膜蛋白的結構。比如，在人工合成的磷脂雙分子層、生物膜提取物的環境中來研究膜蛋白結構。儘管固體核磁共振技術在膜蛋白三維結構研究方面具有獨特的優勢和良好的發展前景，但是由於起步較晚，該技術還有一些亟待解決的問題，其中一個重要瓶頸是難以獲得足夠數量的高質量長程距離約束條件，這嚴重阻礙了固體核磁共振的蛋白質三維結構的解析。
武漢物數所楊俊研究組的博士研究生李建平等與南開大學和澳大利亞國立大學合作，在固體核磁共振中建立和發展了一種PCS-Rosseta的蛋白質高分辨三維結構解析方法。通過引入一種分子探針在蛋白分子上的各個原子核產生了贗接觸位移（Pseudocontact Shifts，PCS）效應，得到的PCS值可以提供豐富的、高質量的結構和角度約束條件。僅利用PCS所提供的結構約束，並結合Rosetta的計算方法計算得到了高分辨的蛋白質三維結構。PCS-Rosetta方法在獲得長程距離約束方面具有數量多、高效率和高質量的優點，在魔角旋轉固體核磁解析膜蛋白高分辨三維結構中具有很大的潛力。
該研究得到了國家自然科學基金委、國家科技部和中國科學院的重點支持。（生物谷Bioon.com）
Magic Angle Spinning NMR Structure Determination of Proteins from Pseudocontact Shifts
Jianping Li †, Kala Bharath Pilla §, Qingfeng Li ‡, Zhengfeng Zhang †, Xuncheng Su ‡, Thomas Huber §, and Jun Yang *†
Magic angle spinning solid-state NMR is a unique technique to study atomic-resolution structure of biomacromolecules which resist crystallization or are too large to study by solution NMR techniques. However, difficulties in obtaining sufficient number of long-range distance restraints using dipolar coupling based spectra hamper the process of structure determination of proteins in solid-state NMR. In this study it is shown that high-resolution structure of proteins in solid phase can be determined without the use of traditional dipolar–dipolar coupling based distance restraints by combining the measurements of pseudocontact shifts (PCSs) with Rosetta calculations. The PCSs were generated by chelating exogenous paramagnetic metal ions to a tag 4-mercaptomethyl-dipicolinic acid, which is covalently attached to different residue sites in a 56-residue immunoglobulin-binding domain of protein G (GB1). The long-range structural restraints with metal-nucleus distance of up to 20 Å are quantitatively extracted from experimentally observed PCSs, and these are in good agreement with the distances back-calculated using an X-ray structure model. Moreover, we demonstrate that using several paramagnetic ions with varied paramagnetic susceptibilities as well as the introduction of paramagnetic labels at different sites can dramatically increase the number of long-range restraints and cover different regions of the protein. The structure generated from solid-state NMR PCSs restraints combined with Rosetta calculations has 0.7 Å root-mean-square deviation relative to X-ray structure..