[Structural compatibility of hydration shells as a criterion of mutual recognition of reacting biomolecules]

Before a biochemical reaction begins to occur reagents need to recognize each other. To explain the recognition mechanism the "key-lock" hypothesis has been proposed at the end of the nineteenth century. Now it should be reconsidered since in the overwhelming majority of cases surface landscapes of the interacting molecules -- individually and in the complex -- do not coincide. The subsequent modifications of this hypothesis, for instance, the ligand-induced adjustment, were unable to predict a degree of the partner affinity and alleviate decision-making in essential task as to the search for the new drug forms. Here we offer a concept according to which the approaching reagents recognize each other by their hydration shells. Such an approach is based on the existence of universal structural blocks in water skeleton of biomolecules. The mutual recognition occurs when hydration shells of reagents are structurally compatible. This statement is demonstrated by the example of the simplest biochemical reaction.