title: Anion-π interactions in complexes of proteins and halogen-containing amino acids.
abstract: We analyzed the potential influence of anion-π interactions on the stability of complexes of proteins and halogen-containing non-natural amino acids. Anion-π interactions are distance and orientation dependent and our ab initio calculations showed that their energy can be lower than -8 kcal mol(-1), while most of their interaction energies lie in the range from -1 to -4 kcal mol(-1). About 20 % of these interactions were found to be repulsive. We have observed that Tyr has the highest occurrence among the aromatic residues involved in anion-π interactions, while His made the least contribution. Furthermore, our study showed that 67 % of total interactions in the dataset are multiple anion-π interactions. Most of the amino acid residues involved in anion-π interactions tend to be buried in the solvent-excluded environment. The majority of the anion-π interacting residues are located in regions with helical secondary structure. Analysis of stabilization centers for these complexes showed that all of the six residues capable of anion-π interactions are important in locating one or more of such centers. We found that anion-π interacting residues are sometimes involved in simultaneous interactions with halogens as well. With all that in mind, we can conclude that the anion-π interactions can show significant influence on molecular organization and on the structural stability of the complexes of proteins and halogen-containing non-natural amino acids. Their influence should not be neglected in supramolecular chemistry and crystal engineering fields as well.
authors.affiliation: Department of Chemistry, Faculty of Veterinary Medicine, University of Belgrade, Belgrade, Serbia.
authors.forename: Sunčica Z
authors.initials: SZ
authors.lastname: Borozan
authors.affiliation: Faculty of Chemistry, University of Belgrade, Belgrade, Serbia.
authors.forename: Mario V
authors.initials: MV
authors.lastname: Zlatović
authors.affiliation: ICTM-Department of Chemistry, University of Belgrade, Belgrade, Serbia. srdjanst@chem.bg.ac.rs.
authors.forename: Srđan Đ
authors.initials: SĐ
authors.lastname: Stojanović
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D000838:Anions / Q000737:chemistry; D006219:Halogens / Q000737:chemistry*; D011506:Proteins / Q000737:chemistry*; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D000596:Amino Acids; D000838:Anions; D006219:Halogens; D011506:Proteins
keywords: Anion–π interactions; Halogen-containing amino acids; Interaction energy; Proteins; Stabilization centers