Influence of C-H...π Hydrogen Bonds in Interleukins

We have explored the roles played by C-H...pi hydrogen bonds in interleukins. Main-chain to side-chain C-H...pi interactions are the predominant type of interactions in interleukins. There was an average of 15 C-H...pi interactions per protein and also there was an average of one significant C-H...pi interaction for every 14 residues in the interleukins investigated. Significant contribution to C-H...pi interactions was only from Asp, Gly, His, Lys, Phe, Pro, Ser, Thr, Trp and Tyr in interleukins. Trp contributed both donor and acceptor atoms in main-chain to side-chain, main-chain to side-chain 5 member aromatic ring and side-chain to side-chain C-H...pi interactions. Short and medium-range C-H...pi interactions are the predominant type of interactions in interleukins. More than 50% of C-H...pi interacting residues had a conservation score of > or = 6. Significant percentage of C-H...pi interacting residues had one or more stabilization centers; hence these residues may also contribute additional stability to structure of interleukins.