Affinity and Selectivity of Peptides for Inorganic Materials: A Thermodynamic Discussion of the Role of Conformational Flexibility

The recognition of inorganic materials by polypeptides is a technologically relevant and scientifically intriguing phenomenon. Several features of the polypeptide determine the affinity for a given surface and, possibly, its selectivity among a set of materials or among various crystal planes of the same material. Different amino acids have different intrinsic affinities for a given surface; the geometrical features of the surface are also relevant in the recognition process. By means of a minimal, analytically solvable thermodynamic model for the polypeptide-surface interaction, we discuss the role of the conformational flexibility in determining affinity and selectivity of polypeptides for surfaces. In particular, the interplay between geometrical matching of polypeptide-surface features and the presence in the polypeptide of amino acids able to bind the target surface is analyzed as a function of the flexibility. A discussion of literature data in the light of this minimal model is also given.