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Osmosis is the spontaneous net movement of solvent molecules through a semi-permeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides.
Protein hydration is very important for their three-dimensional structure, dynamic ensemble of conformations [2249] and activity [472, 1093, 1345, 2005]. Indeed, proteins lack biological activity in the absence of sufficient hydrating water (usually at least a monolayer covering; > 1.5 mols H2O mol-1 aminoacid residue). The aqueous structuring around proteins is affected out to at least 1 - 1.5 nm from its surface or 2 - 3 nm between neighboring proteins, as shown by terahertz spectroscopy [1368, 2102], e with even small proteins (e.g. bovine serum albumin, 66,463 Da) affecting the whole of its unstirred (Nernst) layer of about 20,000 neighboring water molecules [2102]. In solution, proteins possess a conformational flexibility, which encompasses a wide range of hydration states, not seen in the crystal a or in non-aqueous environments. Equilibrium between these states will depend on the activity of the water within its microenvironment; that is, the freedom that the water has to hydrate the protein [434]. Thus, protein conformations demanding greater hydration are favored by more (re-)active water (for example, high density water containing many weak bent and/or broken hydrogen bonds) and 'drier' conformations are relatively favored by lower activity water (for example, low-density water containing many strong intra-molecular aqueous hydrogen bonds).
The partnership of water and organics in life is connected to hydrogen bonding, especially in water. Anything dissolved in water or in surface contact with water, will impact the hydrogen bonding of bulk water. The degree of residual hydrating power in the water, after things are added, is called activity which is defines as 1.0 for pure water. As we add things to the water, the activity of the water will decrease. This change in activity of the water, both locally (local material) and globally (summation), allows the water to control and coordinate enzyme shapes and kinetics.
Movement of signals in water is super fast, since it can be transmitted as energy signals through the binary switches of the hydrogen bonds. No hydrogen bonds ever has to break. This is really slick since the activity; hydration, gradients can stay very tight, while information is being moved around the cell. Water can also use quantum tunneling, if need be, to transmit information and activity changes, across barriers. Membranes pose little problem, but can be used for some time delay features.