Fujiwara M, Kato T, Yamazaki T, Yamasaki K, Nagayam K
Analytical Engineering Department. JEOL DATUM Ltd, Akishima, Tokyo, Japan.
Biol Pharm Bull. 2000 Oct;23(10):1147-52. doi: 10.1248/bpb.23.1147.
The solution structure of ribonuclease HI (RNase HI) from Escherichia coli (E. coli), a protein of 155 residues, was determined. Three-dimensional nuclear Overhauser enhancement spectroscopy (NOESY) was used to obtain 1,424 distance constraints between individually assigned polypeptide chain hydrogen atoms. Supplemental geometric constraints of 90phi angles and 12chi1 angles, and the distance constraints of 66 hydrogen bonds were experimentally derived. Using the DADAS90 program that calculates structures in dihedral angle space, 15 structures satisfying almost all constraints were obtained. The average root mean square deviation (RMSD) from the mean structure was 0.75 A for backbone atoms. The RMSD for backbone atoms between the representative NMR structure with the smallest constraint violation and crystal structures was within 1.2 A. Although the NMR and crystal structures thus resemble one another, a significant discrepancy was observed in a region termed 'basic protrusion.' The discrepancy observed in NMR experiments is explained by fluctuation in this region.
已确定来自大肠杆菌（E. coli）的核糖核酸酶HI（RNase HI）的溶液结构，该蛋白质由155个残基组成。利用三维核Overhauser增强光谱法（NOESY）获得了单个分配的多肽链氢原子之间的1424个距离约束。通过实验得出了90个phi角和12个chi1角的补充几何约束以及66个氢键的距离约束。使用在二面角空间中计算结构的DADAS90程序，获得了15个几乎满足所有约束的结构。主链原子相对于平均结构的平均均方根偏差（RMSD）为0.75埃。具有最小约束违反的代表性NMR结构与晶体结构之间主链原子的RMSD在1.2埃以内。尽管NMR结构和晶体结构因此彼此相似，但在一个称为“碱性突出部”的区域观察到了显著差异。NMR实验中观察到的差异可通过该区域的波动来解释。
