Protein-Solvent Interactions And Biological Functions. Models From Statistical Physics.

We consider two simple biosystems, both exhibiting biological function at room temperature: (1) hydrated protein powders, and (2) pearly anhydrous enzymes in alcohol, and we propose a common structure of the solvent-protein interface. We extend our previous treatment of percolation to the "blobs, nodes and links" model, to describe the surface as patches of H-bonded OH groups, singly connected in the percolating backbone. A dynamical pathway between surface and core is identified in few strong H-bonds between charged side chains and protein secondary structure. Since recent work in collaboration with F. Bruni and G. Consolini shows dielectric behaviour typical of proton glasses, we model proton frustration in blobs by a 2D Ising net, and in collaboration with D. Stauffer we find by Q2R cellular automata that this system fails to reach internal equilibrium. A functional relevance for non-ergodicity in enzymatic activity is proposed.