ABSTRACT
We are about to finish the journey that has transported us from the very basics of the isolated water molecule to interfacial water on both ideal and real systems (mainly inorganic). We face in this last chapter the extremely challenging job of understanding water in the most important system, life (as we know it), but restricted to interfaces. In fact this restriction is not limiting at all because biological liquids are characterized by having a rather high concentration of large solutes (biomolecules), so that a large fraction of water molecules resides for a sufficiently long time in the hydration shell: in biosystems interfacial water relegates bulk water to a secondary role. In the simplest picture of the process, the water molecules are static at the interface but this visualization is wrong: hydration is a dynamic process, in the ps range, the timescale of H-bonding. Within the introductory scope of this book, and particularly targeted to the nonexpert in the field, we browse through the sequence of increasing degrees of complexity covering amino acids, peptides, small proteins, nucleic acids, and membranes, concentrating on a few representative examples.
