Computation of non covalent interactions in iNOS proteins: A gene expressed by phagocytosis by macrophage cells in prosthetic particulate debris

Nitric oxide is known to be one of the principal mediators of action of many cytokines. The possibility of inducible nitric oxide (iNOS) synthase expression from macrophage is widely studied. This work comprises of numerical computation of the non-covalent interactions in 15 iNOS proteins from the Protein Data Bank (PDB) through the cation–π interactions in them. It was observed that among all the 15 iNOS proteins studied Arg has a higher composition than Lys but the cation–π interaction was almost similar in all the 15 iNOS proteins studied. Also, all the 15 iNOS protein had a higher electrostatic energy than the van der Waals energy. Moreover, there was no Lys–Tyr pair involved in the cation–π interaction in any of the iNOS protein studied. On the other hand the Arg–Trp pair had the strongest contribution towards cation–π interactions as compared to other pairs. The long range interactions among residues were predominant in all the 15 iNOS studied in this work. These results may be of great significance in the correlation of the non-covalent interaction in the inflammatory genes /cytokines with the aseptic loosening of implants. Ours is the first report on this kind of a non-covalent interaction studies on such inflammatory genes, generally expressed by macrophage during interaction with the prosthetic wear debris.