title: Nature of cation-pi interactions and their role in structural stability of immunoglobulin proteins.
abstract: Cation-pi interactions are known to be important contributors to protein stability and ligand-protein interactions. In this study, we have analyzed the influence of cation-pi interactions in single chain immunoglobulin proteins. We observed 87 cation-pi interactions in a data set of 33 proteins. These interactions are mainly formed by long-range contacts, and there is preference of Arg over Lys in these interactions. Arg-Tyr interactions are predominant among the various pairs analyzed. Despite the scarcity of interactions involving Trp, the average energy for Trp-cation interactions is quite high. This information suggests that the cation-pi interactions involving Trp might be of high relevance to the proteins. Secondary structure analysis reveals that cation-pi interactions are formed preferably between residues in which at least one is in beta-strand. Proteins having beta-strand regions have the highest number of cation-pi interaction-forming residues.
authors.affiliation: Vellore Institute of Technology, Tamil Nadu, India. iftikharaslamtayubi@vit.ac.in
authors.forename: I A
authors.initials: IA
authors.lastname: Tayubi
authors.forename: R
authors.initials: R
authors.lastname: Sethumadhavan
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002412:Cations / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry* / Q000378:metabolism; D008968:Molecular Conformation; D055550:Protein Stability; D017433:Protein Structure, Secondary
chemical_list: D000596:Amino Acids; D002412:Cations; D007136:Immunoglobulins