Angewandte Chemie International Edition · 2005 · 104 citations · 32 references
Life SciencesBiochemistryChemistryProtein BiochemistryStructural BiologyStructure-activity RelationshipsCoordination ChemistryLigand BindingProtein StructureProtein-ligand BindingProtein-ligand InteractionsProtein-ligand RecognitionCation InteractionsCation-π InteractionsEnthalpyLigand-binding EnergeticsProtein-ligand Binding Free EnergyProtein-ligand ComplexesQuaternary Ammonium Compoundsπ Interactions
The aromatic box formed by the side chains Phe 174, Tyr 99, and Trp 215 in the S4-pocket of Factor Xa is a very effective onium binding site (see picture; red O, blue N, green Cligand, gray Cprotein). The free enthalpy increment for cation–π interactions between quaternary ammonium ions and aromatic groups in this box is determined to be ΔΔG=2.8 kcal mol−1. Database searches reveal that similar cation binding sites are not uncommon in biological systems.
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