Fraenkel Y, Gershoni J M, Navon G
School of Chemistry, Tel-Aviv University, Ramat-Aviv, Israel.
Biochemistry. 1994 Jan 25;33(3):644-50. doi: 10.1021/bi00169a004.
A complete 1H assignment of d-tubocurarine was carried out using 1D and 2D NMR techniques. Geometries of free acetylcholine (ACh) and d-tubocurarine were compared with those of the ligands bound to a recombinant cholinergic binding site (T alpha 184-200 expressed as a fusion protein in Escherichia coli). The conformations of the free ligands were determined by NOESY experiments while those of the bound molecules were obtained by transferred NOESY. The complete relaxation matrix was solved yielding distance constraints which were further refined by a sigma back-calculation. ACh bound to recombinant T alpha 184-200 closely resembled the conformation previously reported for ACh bound to the intact receptor. d-Tubocurarine in the bound state undergoes extensive induced conformational rearrangements generating a "cup"-shaped structure. A unique positively charged hydrophobic domain is identified as characteristic of both bound cholinergic ligands.
使用一维和二维核磁共振技术对d -筒箭毒碱进行了完整的¹H归属。将游离乙酰胆碱（ACh）和d -筒箭毒碱的几何结构与结合到重组胆碱能结合位点（在大肠杆菌中作为融合蛋白表达的Tα184 - 200）的配体的几何结构进行了比较。通过NOESY实验确定游离配体的构象，而通过转移NOESY获得结合分子的构象。求解完整的弛豫矩阵得到距离约束，通过σ反计算进一步优化。与重组Tα184 - 200结合的ACh与先前报道的与完整受体结合的ACh的构象非常相似。处于结合状态的d -筒箭毒碱经历广泛的诱导构象重排，形成“杯”状结构。一个独特的带正电荷的疏水结构域被确定为两种结合的胆碱能配体的特征。
