Carugo Oliviero
Department of Chemistry, University of Pavia, viale Taramelli 12, I-27100 Pavia, Italy; Department of Structural and Computational Biology, Vienna University, Campus Vienna Biocenter, A-1030 Vienna, Austria.
Int J Biol Macromol. 2017 Jun;99:160-165. doi: 10.1016/j.ijbiomac.2017.02.073. Epub 2017 Feb 23.
The positions of water molecules have been analyzed in high quality protein X-ray crystal structures. About 70% of these water molecules are in contact with protein atoms at the protein surface and constitute the first hydration layer. About 20% of them are close to the first hydration layer but are not in contact with protein atoms and constitute the second hydration layer. The rest of the water molecules are either buried in the protein core or close to hetero-atoms (inorganic ions and small organic molecules). Upper layers (third, fourth, etc.) are not observed in the dataset of protein crystal structures examined here. Water molecules of both layers are not, in general, surrounded by a tetrahedral arrangement of atoms, as it should be expected on the basis of the electronic structure of water. Usually there are less than four atoms around water molecules and even when there are four atoms, the stereochemistry is often distorted. Water molecules are more mobile than protein atoms, more in the second hydration layer than in the first.
已在高质量蛋白质X射线晶体结构中分析了水分子的位置。这些水分子中约70%在蛋白质表面与蛋白质原子接触，构成第一水化层。约20%的水分子靠近第一水化层，但不与蛋白质原子接触，构成第二水化层。其余水分子要么埋在蛋白质核心中，要么靠近杂原子（无机离子和小有机分子）。在此处检查的蛋白质晶体结构数据集中未观察到上层（第三层、第四层等）。通常，两层的水分子并非如基于水的电子结构所预期的那样被四面体排列的原子所包围。水分子周围通常少于四个原子，即使有四个原子，其立体化学结构也常常扭曲。水分子比蛋白质原子更具流动性，在第二水化层中比在第一水化层中更甚。
