Protein structure determination using NMR is dependent on experimentally acquired distance restraints. Often, however, an insufficient number of these restraints are available for determining a protein’s correct fold, much less its detailed three-dimensional structure. In consideration of this problem, we propose a simple means to acquire supplemental structural restraints from protein surface accessibilities using solvent saturation transfer to proteins (SSTP), based on the principles of paramagnetic chemical-exchange saturation transfer. Here, we demonstrate the utility of SSTP in structure calculations of two proteins, TSG101 and ubiquitin. The observed SSTP was found to be directly proportional to solvent accessibility. Since SSTP does not involve the direct excitation of water, which compromises the analysis of protein protons entangled in the breadth of the water resonance, it has an advantage over conventional water-based magnetization transfers. Inclusion of structural restraints derived from SSTP improved both the precision and accuracy of the final protein structures in comparison to those determined by traditional approaches, when using minimal amounts of additional structural data. Furthermore, we show that SSTP can detect weak protein–protein interactions which are unobservable by chemical shift perturbations.
使用核磁共振测定蛋白质结构取决于实验获得的距离约束。然而,通常情况下,这些约束的数量不足以确定蛋白质的正确折叠,更不用说其详细的三维结构了。考虑到这个问题,我们提出了一种简单的方法,即基于顺磁
化学交换饱和转移原理,使用溶剂饱和转移到蛋白质(SSTP)从蛋白质表面可及性获得补充结构约束。在这里,我们展示了SSTP在
TSG101和泛素两种蛋白质的结构计算中的实用性。观察到的SSTP与溶剂可及性成正比。由于SSTP不涉及对
水的直接激发,这会影响对蛋白质质子在
水共振中的纠缠的分析,因此它比传统的基于
水的磁化转移具有优势。与使用传统方法确定的蛋白质结构相比,当使用最少量的附加结构数据时,包含从SSTP得出的结构约束可以提高最终蛋白质结构的精确度和准确性。此外,我们表明SSTP可以检测到
化学位移扰动无法观察到的弱蛋白质-蛋白质相互作用。