Protein-protein interfaces: properties, preferences, and projections.

Herein, we study the interfaces of a set of 146 transient protein-protein interfaces in order to better understand the principles of their interactions. We define and generate the protein interface using tools from computational geometry and topology and then apply statistical analysis to its residue composition. In addition to counting individual occurrences, we evaluate pairing preferences, both across and as neighbors on one side of an interface. Likelihood correction emphasizes novel and unexpected pairs, such as the His-Cys pair found in most complexes of serine proteases with their diverse inhibitors and the Met-Met neighbor pair found in unrelated protein interfaces. We also present a visualization of the protein interface that allows for facile identification of residue-residue contacts and other biochemical properties.