WATER-STRUCTURE IN CUBIC INSULIN CRYSTALS
WATER-STRUCTURE IN CUBIC INSULIN CRYSTALS
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DOI：
10.1073/pnas.88.2.622
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发表时间：
1991-01-01
影响因子：
11.1
通讯作者：
CASPAR, DLD
中科院分区：
文献类型：
--
作者：
BADGER, J;CASPAR, DLD
在立方胰岛素晶体结构，它占据了65%的体积，溶剂的电子密度分布已被映射从1.7埃分辨率的衍射数据通过迭代差分傅立叶方法，使用先前确定的蛋白质结构作为细化约束。 从来自蛋白质和平坦溶剂模型的相开始，将根据数据计算的差异图添加到蛋白质包络之外，然后使用修改的图重新计算迭代细化的相。 用模型数据、用实验数据和变体蛋白质模型以及通过进行溶剂图的部分细化来测试该方法，表明细化算法在数据的噪声水平内产生用于溶剂密度的可靠值。 在整个溶剂空间中观察到密度的波动，表明水分子的非随机排列从与蛋白质表面接触的有序水合壳延伸了几层。 这样的排序可以解释水合力对抗亲水表面的紧密接近和活结构中的其他长程水依赖性相互作用。
The electron density distribution of the solvent in the cubic insulin crystal structure, which occupies 65% of the volume, has been mapped from 1.7-angstrom resolution diffraction data by an iterative difference Fourier method, using the previously determined protein structure as the refinement restraint. Starting with phases from the protein and a flat solvent model, the difference map calculated from the data was added outside the protein envelope, and the modified map was then used to recalculate phases for the iterative refinement. Tests of the method with model data, with the experimental data and a variant protein model, and by carrying out a partial refinement of the solvent map demonstrate that the refinement algorithm produces reliable values for the solvent density within the noise level of the data. Fluctuations in density are observed throughout the solvent space, demonstrating that nonrandom arrangements of the water molecules extend several layers from the well-ordered hydration shell in contact with the protein surface. Such ordering may account for the hydration force opposing close approach of hydrophilic surfaces and other long-range water-dependent interactions in living structures.