CH/π Interactions as demonstrated in the crystal structure of guanine-nucleotide binding proteins, Src homology-2 domains and human growth hormone in complex with their specific ligands Original Research Article

The CH/π interaction is a weak attractive molecular force occurring between CH groups and π-systems. Possibility has been examined for the role of CH/π interaction, by use of a computer program, in the crystallographic data of several guanine-nucleotide binding proteins, src homology-2 domains and human growth hormone complexed with their specific ligands. Short CH/π contacts have been found in every case where cohesive forces are expected. Comparison of the structures of functionary related proteins has shown that mutation may occur but necessary CH/π interactions are conserved. A considerable part of the non-polar interactions, broadly ascribed in the past to the van der Waals interaction or the so-called hydrophobic effect, has been suggested to be attributed to a more specific attractive force, the CH/π interaction.