中文摘要：

生物大分子是构成生命的物质基础,在其天然环境——水溶液中一般以精确的超分子结构存在.迄今,人们已经合成了种类繁多的水溶性高分子.然而,鲜有合成高分子能够在水溶液中完成精确的超分子组装.与合成高分子相比,生物大分子是特殊而神奇的.为了研究生物大分子与水的相互作用,近年来作者以单分子力谱为主要的实验方法,开展了生物大分子在水溶液与非极性溶剂中的对照研究.研究表明,在非极性溶剂中,生物大分子的超分子结构失稳,转变为无超分子结构的状态.水是一个重要的开关,调控着生物大分子的超分子结构和功能.作者据此提出了生物大分子的水环境适应性概念和早期化学进化过程中水环境筛选生物大分子的假说,并认为水环境适应性是生物大分子和合成水溶性高分子的分水岭.对水和生物大分子的深入研究,将有望破解生命的更多奥秘.

英文摘要：

Biomacromolecules are the foundation of life. In the natural environment （aqueous solution） , the biomacromolecules exist in the precise supramolecular structures. To date, many kinds of water soluble polymers have been synthesized. However, few of them can be self-assembled into precise supramoleeular structures in aqueous solution. Compared to synthetic polymers, biomacromolecules are special and magic. Recently,the author＇s group utilized single-molecule force spectroscopy （SMFS） to study the interactions between biomacromolecules and water. For ssDNA,there is an evident deviation between the single-chain force- extension （F-E） curves obtained respectively in the aqueous solution and nonpolar solvent,which is estimated to be 0.58kBT per base in energy. Comparing to synthetic water soluble polymers,this energy is rather low. The weak competition influence of water may be a precondition for a stable dsDNA to exist in water. For dsDNA, the double-helix structure will be unwound when it is dragged across the water/nonpolar solvent interface. For a polyprotein （polyI27）, the unfolding of the globules in water can be observed as saw-tooth F-E curve. However,the same sample in nonpolar solvent only presents an pure elastic behaviour similar to that of polypeptide. Similarly,a clear deviation can also be observed when comparing the single-molecule F-E curves of other biomacromolecules （such as RNA and natural cellulose） obtained respectively in the aqueous solution and nonpolar solvent. It was shown that in nonpolar solvents, the supramolecular structures of biomacromolecutes will be unstable,resulting in the denaturation of the biomacromolecules. Water is the switch that regulates the supramolecular structures and functions of biomacromolecules. The concept of aqueous environment adaptability is proposed. It is speculated that biomacromolecules were selected by the aqueous environment during the early chemical evolution. The aqueous environment adaptability may be one important division between