title: Hydrogen bonds with pi-acceptors in proteins: frequencies and role in stabilizing local 3D structures.
abstract: A comprehensive structural analysis of X--H...pi hydrogen bonding in proteins is performed based on 592 published high-resolution crystal structures (< or = 1.6 A). All potential donors and acceptors are considered, including acidic C--H groups. The sample contains 1311 putative X--H...pi hydrogen bonds with N--H, O--H or S--H donors, that is about one per 10.8 aromatic residues. By far the most efficient pi-acceptor is the side-chain of Trp, which accepts one X--H...pi hydrogen bond per 5.7 residues. The focus of the analysis is on recurrent structural patterns involving regular secondary structure elements. Numerous examples are found where peptide X--H...pi interactions are functional in stabilization of helix termini, strand ends, strand edges, beta-bulges and regular turns. Side-chain X--H...pi hydrogen bonds are formed in considerable numbers in alpha-helices and beta-sheets. Geometrical data on various types of X--H...pi hydrogen bonds are given.
authors.affiliation: Institut für Chemie--Kristallographie, Freie Universität Berlin, Takustrasse 6, D-14195 Berlin, Germany. steiner@chemie-fu-berlin.de
authors.forename: T
authors.initials: T
authors.lastname: Steiner
authors.forename: G
authors.initials: G
authors.lastname: Koellner
mesh_terms: D000818:Animals; D002244:Carbon / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D019992:Databases as Topic; D006801:Humans; D006859:Hydrogen / Q000737:chemistry / Q000378:metabolism; D006860:Hydrogen Bonding; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D013816:Thermodynamics; D014364:Tryptophan / Q000378:metabolism; D014867:Water / Q000737:chemistry / Q000378:metabolism
chemical_list: D011506:Proteins; D014867:Water; D002244:Carbon; D006859:Hydrogen; D014364:Tryptophan