WATER TRANSFER ENERGETICS AND SOLID-LIKE PACKING OF GLOBULAR-PROTEINS

In this article we generalize the use of a relationship based on the o ccurrence of some characteristic temperatures in protein unfolding, wh ich were originally highlighted for proteins showing the unfolding ent halpy-entropy convergence. On this basis, we show how to dissect the u nfolding Gibbs energy of globular proteins in terms of solid-like and liquid-like contributions, untangling the protein energetics by a sche me which does not suffer from excessive intricacy. We also provide an experimental estimate of unfavorable polar contributions to the protei n stability, by which it seems possible to evaluate the number of buri ed residues in individual proteins. A comparison is assessed with the so-called hard sphere model of globular proteins. Results seem to reco ncile the view that the protein interior is liquid-like with the obser vation that protein organization resembles an assembly of closely pack ed spheres. (C) 1995 Wiley-Liss, Inc.