Glaubitz C, Gröger A, Gottschalk K, Spooner P, Watts A, Schuldiner S, Kessler H
Department of Biochemistry, University of Oxford, UK.
FEBS Lett. 2000 Sep 1;480(2-3):127-31. doi: 10.1016/s0014-5793(00)01916-5.
The binding of tetraphenylphosphonium (TPP+) to EmrE, a membrane-bound, 110 residue Escherichia coli multidrug transport protein, has been observed by 31P cross-polarisation-magic-angle spinning nuclear magnetic resonance spectroscopy (CP-MAS NMR). EmrE has been reconstituted into dimyristoyl phosphatidylcholine bilayers. CP-MAS could selectively distinguish binding of TPP+ to EmrE in the fluid membrane. A population of bound ligand appears shifted 4 ppm to lower frequency compared to free ligand in solution, which suggests a rather direct and specific type of interaction of the ligand with the protein. This is also supported by the observed restricted motion of the bound ligand. The observation of another weakly bound substrate population arises from ligand binding to negatively charged residues in the protein loop regions.
通过31P交叉极化 - 魔角旋转核磁共振光谱法（CP - MAS NMR）观察到四苯基鏻（TPP +）与EmrE（一种膜结合的、含有110个残基的大肠杆菌多药转运蛋白）的结合。EmrE已被重构到二肉豆蔻酰磷脂酰胆碱双层膜中。CP - MAS能够选择性地区分TPP +在流体膜中与EmrE的结合。与溶液中的游离配体相比，结合的配体群体的频率出现了4 ppm的低频位移，这表明配体与蛋白质之间存在一种相当直接和特异性的相互作用类型。结合配体受限运动的观察结果也支持了这一点。另一个弱结合底物群体的观察结果源于配体与蛋白质环区域中带负电荷残基的结合。
