Lazar Louis M, Fisher S Zoe, Moulin Aaron G, Kovalevsky Andrey, Novak Walter R P, Langan Paul, Petsko Gregory A, Ringe Dagmar
Department of Biochemistry and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, 415 South Street, Waltham, MA 02454, USA.
Acta Crystallogr Sect F Struct Biol Cryst Commun. 2011 May 1;67(Pt 5):587-90. doi: 10.1107/S1744309111009341. Epub 2011 Apr 27.
The overarching goal of this research project is to determine, for a subset of proteins, exact hydrogen positions using neutron diffraction, thereby improving H-atom placement in proteins so that they may be better used in various computational methods that are critically dependent upon said placement. In order to be considered applicable for neutron diffraction studies, the protein of choice must be amenable to ultrahigh-resolution X-ray crystallography, be able to form large crystals (1 mm(3) or greater) and have a modestly sized unit cell (no dimension longer than 100 Å). As such, γ-chymotrypsin is a perfect candidate for neutron diffraction. To understand and probe the role of specific active-site residues and hydrogen-bonding patterns in γ-chymotrypsin, neutron diffraction studies were initiated at the Protein Crystallography Station (PCS) at Los Alamos Neutron Science Center (LANSCE). A large single crystal was subjected to H/D exchange prior to data collection. Time-of-flight neutron diffraction data were collected to 2.0 Å resolution at the PCS with ~85% completeness. Here, the first time-of-flight neutron data collection from γ-chymotrypsin is reported.
本研究项目的总体目标是，针对一部分蛋白质，利用中子衍射确定其精确的氢原子位置，从而改进蛋白质中氢原子的定位，以便能更好地用于各种严重依赖该定位的计算方法。为了被认为适用于中子衍射研究，所选蛋白质必须适合超高分辨率X射线晶体学，能够形成大晶体（1立方毫米或更大）且具有适度大小的晶胞（任何维度不超过100埃）。因此，γ-胰凝乳蛋白酶是中子衍射的理想候选对象。为了理解和探究γ-胰凝乳蛋白酶中特定活性位点残基和氢键模式的作用，在洛斯阿拉莫斯中子科学中心（LANSCE）的蛋白质晶体学站（PCS）开展了中子衍射研究。在数据收集之前，对一个大单晶进行了氢/氘交换。在PCS以约85%的完整性收集了飞行时间中子衍射数据，分辨率达到2.0埃。本文报道了首次从γ-胰凝乳蛋白酶收集到的飞行时间中子数据。
