Harrison R W, Wlodawer A, Sjölin L
Center for Chemical Physics, National Bureau of Standards, Gaithersburg, MD 20899.
Acta Crystallogr A. 1988 May 1;44 ( Pt 3):309-20. doi: 10.1107/s010876738701242x.
A method has been developed to determine the structure of bound solvent and the positions of exchanged hydrogens in proteins, on the basis of neutron diffraction from hydrogenous and deuterated crystals. In this method phases for the hydrogenous and for the deuterated model are refined simultaneously, and an average model is imposed in the volume occupied by non-hydrogen atoms. The densities in the areas of bulk solvent are replaced by their average values, while no modifications are performed in the vicinity of ordered solvents and potentially exchangeable hydrogens. The method was tested on 1.8 A neutron diffraction data collected from two crystals of bovine pancreatic trypsin inhibitor, one of them deuterated and the other hydrogenous. Significant improvement was observed for the densities corresponding to many partially occupied solvent sites, as well as to partially exchanged hydrogens. The algorithm presented here has been compared with a different approach published recently by Shpungin & Kossiakoff [Methods Enzymol.(1986), 127, 329-342].
已开发出一种方法，可基于含氢晶体和氘代晶体的中子衍射来确定蛋白质中结合溶剂的结构以及交换氢的位置。在该方法中，含氢模型和氘代模型的相位同时进行精修，并在非氢原子占据的体积中施加一个平均模型。大量溶剂区域的密度被其平均值取代，而在有序溶剂和潜在可交换氢附近不进行修改。该方法在从牛胰蛋白酶抑制剂的两个晶体收集的1.8埃中子衍射数据上进行了测试，其中一个晶体是氘代的，另一个是含氢的。对于许多部分占据的溶剂位点以及部分交换氢对应的密度，观察到了显著改善。这里提出的算法已与Shpungin和Kossiakoff最近发表的一种不同方法[《酶学方法》(1986年)，127卷，329 - 342页]进行了比较。
