title: Photophysics of a Fluorescent Non-natural Amino Acid: p-Cyanophenylalanine.
abstract: The non-natural amino acid p-cyanophenylalanine (Phe(CN)) has recently emerged as a useful fluorescent probe of proteins; however, its photophysical properties have not been systematically examined. Herein, we measure the fluorescence quantum yield and the fluorescence lifetime of Phe(CN) in a series of solvents. It is found that the fluorescence lifetime of Phe(CN) shows a linear dependence on the Kamlet-Taft parameter α of the protic solvents used, indicating that the solute-solvent hydrogen bonding interactions mediate the non-radiative decay rate. Thus, results of this study provide a basis for quantitative application of Phe(CN) fluorescence in protein conformational studies.
authors.affiliation: Department of Chemistry, University of Pennsylvania, 231 South 34  Street, Philadelphia, PA 19104, USA.
authors.forename: Arnaldo L
authors.initials: AL
authors.lastname: Serrano
authors.forename: Thomas
authors.initials: T
authors.lastname: Troxler
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Tucker
authors.forename: Feng
authors.initials: F
authors.lastname: Gai