Mechanism Of Interaction Between The Volatile Anesthetic Halothane And A Model Ion Channel Protein: Fluorescence And Infrared Spectroscopy Employing A Cyano-phenylalanine Probe And Molecular Dynamics Simulation

Abstract

We demonstrate that cyano-phenylalanine (PheCN) can be utilized to probe the binding of the inhalational anesthetic halothane to a model ion channel protein hbAP-PheCN possessing a designed binding cavity. The Trp to PheCN mutation adjacent the cavity alters neither the α-helical conformation nor the 4-helix bundle structure. The halothane binding properties of hbAP-PheCN, based on fluorescence quenching, are consistent with those of the Trp-prototype, hbAP1. The dependence of fluorescence lifetime on halothane concentration implies a one-dimensional diffusion of halothane along the nonpolar core of the protein bundle.