Heteropolymer sequence design and preferential solvation of hydrophilic monomers: application of random energy model.

We study the role of the surface of the globule and the role of interactions with the solvent for designed-sequence heteropolymers using the random energy model. We investigate the ground-state energy and surface-monomer composition distribution. By comparing the freezing transition in random and designed-sequence heteropolymers, we discuss the effects of design. Based on our results, we are able to show under which conditions the solvation effect improves the quality of the sequence design. Finally, we study sequence-space entropy and discuss the number of available sequences as a function of the imposed requirements for design quality.