Watermediated

Watermediated is an adjective used across science to describe processes, structures, or interactions in which water acts as a mediator between other species. In chemistry, biochemistry, and related fields, water molecules can bridge functional groups, ions, or macromolecules, forming water-mediated contacts that influence conformation, reactivity, and binding.

In protein–ligand interactions, a water molecule can connect the protein and ligand through multiple hydrogen bonds, altering binding affinity and specificity. Water-mediated catalysis also occurs, with water acting as a proton shuttle or reactant in enzymatic reactions. The Grotthuss mechanism describes rapid proton transfer through networks of solvent water.

In materials science and earth sciences, water-mediated processes describe how water coordinates ions in hydrated minerals or facilitates solute transport through soils, membranes, and porous media. In hydrated polymers and hydrogels, water mediates interactions between chains and additives, affecting mechanical properties and diffusion.

Modeling and experimental characterization often distinguish explicit solvent representations, which include individual water molecules and can reveal bridging waters, from implicit solvent models that approximate solvent effects. Identifying water-mediated contacts is important in X-ray and cryo-EM structures, nuclear magnetic resonance studies, and molecular docking in drug design.

Because water forms a dynamic and context-dependent hydrogen-bond network, water-mediated interactions can vary with temperature, pressure, pH, or solute composition. The term highlights the solvent’s role in mediating interactions, rather than direct contacts alone, and underscores the importance of hydration in structure, reactivity, and function.