Cation-pi interactions involving aromatic amino acids.
The cation-pi interaction is a general, strong, noncovalent binding force that is used throughout nature. The side chains of the aromatic amino acids [phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp)] provide a surface of negative electrostatic potential than can bind to a wide range of cations through a predominantly electrostatic interaction. In this brief overview, the fundamental nature of the cation-pi interaction will be described, relying on fundamental, gas phase studies of the effect. Then, several examples of cation-pi interactions involving aromatic amino acids will be described. These include contributions to protein secondary structure, in which Phe/Tyr/Trp...lysine (Lys)/arginine interactions are common. We will also describe several examples of protein-ligand interactions that make use of cation-pi interactions. We will place special emphasis on the binding of quaternary ammonium ions, such as trimethylated Lys and the neurotransmitter acetylcholine.
Dougherty
Dennis A
DA
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA. dadougherty@caltech.edu
D024322:Amino Acids, Aromatic / Q000737:chemistry*; D002412:Cations; D006657:Histones / Q000737:chemistry; D008958:Models, Molecular; D018377:Neurotransmitter Agents / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry*
D024322:Amino Acids, Aromatic; D002412:Cations; D006657:Histones; D018377:Neurotransmitter Agents; D011506:Proteins