Surface topography dependence of biomolecular hydrophobic hydration
Surface topography dependence of biomolecular hydrophobic hydration
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DOI：
10.1038/33653
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发表时间：
1998-04-16
期刊：
影响因子：
64.8
通讯作者：
Rossky, PJ
中科院分区：
文献类型：
--
作者：
Cheng, YK;Rossky, PJ
许多生物分子的特征在于表面含有扩展的非极性区域（1），并且这些表面的聚集和随后从水中的去除被认为在细胞中的生物分子组装中起关键作用（2）。因此，更好地理解生物分子的疏水水合作用可能会对细胞内组装产生新的见解。传统观点认为，小疏水溶质的水合壳是笼形的，其特征在于局部笼状氢键结构和熵的明显损失（2）。然而，扩展的非极性平面表面的水合似乎涉及相对于笼形水合壳（3，4）取向反转的结构，其中不满足的氢键指向疏水表面。在这里，我们提出了计算机模拟的多肽蜂毒肽和水之间的相互作用，表明这两种不同的水合结构也存在附近的生物分子表面。我们发现，这两种结构的水-水相互作用焓有很大的差异，它们的相对贡献强烈地依赖于蜂毒肽分子的表面形貌：笼形结构占主导地位附近的凸表面补丁，而水化壳附近的平面波动笼形和较低的有序或倒置结构之间。表面形貌对疏水水化的结构和自由能的强烈影响可能在一般情况下保持不变，并且对于许多表面包含凸块、深或浅的凹槽和大致平面区域的生物分子特别重要（5）。
Many biomolecules are characterized by surfaces containing extended nonpolar regions(1), and the aggregation and subsequent removal of such surfaces from water is believed to play a critical role in the biomolecular assembly in cells(2). A better understanding of the hydrophobic hydration of biomolecules may therefore yield new insights into intracellular assembly, Conventional views hold that the hydration shell of small hydrophobic solutes is clathrate-like, characterized by local cage-like hydrogen-bonding structures and a distinct loss in entropy(2). The hydration of extended nonpolar planar surfaces, however, appears to involve structures that are orientationally inverted relative to clathrate-like hydration shells(3,4), with unsatisfied hydrogen bonds that are directed towards the hydrophobic surface. Here we present computer simulations of the interaction between the polypeptide melittin and water that demonstrate that the two different hydration structures also exist near a biomolecular surface. We find that the two structures are distinguished by a substantial difference in the water-water interaction enthalpy, and that their relative contributions depend strongly on the surface topography of the melittin molecule: clathrate-like structures dominate near con-vex surface patches, whereas the hydration shell near flat surfaces fluctuates between clathrate-like and less-ordered or inverted structures. The strong influence of surface topography on the structure and free energy of hydrophobic hydration is likely to hold in general, and will be particularly important for the many biomolecules whose surfaces contain convex patches, deep or shallow concave grooves and roughly planar areas(5).