title: Intensity and anisotropy decays of [Leu5] enkephalin tyrosyl fluorescence by 10 GHz frequency-domain fluorometry.
abstract: The technique of 10 GHz frequency-domain fluorometry was used to resolve the complex picosecond intensity and anisotropy decays of the tyrosyl emission of [Leu5] enkephalin. Enhanced resolution of anisotropy decay was obtained by using acrylamide quenching of the tyrosyl fluorescence and global analysis of the frequency-domain anisotropy data obtained with different amounts of acrylamide. The data indicates a 44 ps correlation time for local tyrosine motions, and a 219 ps correlation time for overall rotational diffusion of the pentapeptide. Our data are consistent with an initial loss of fluorescence anisotropy from r0 = 0.4 to a value of r0 = 0.326 occurring during the first two picoseconds after excitation.
authors.affiliation: University of Maryland School of Medicine, Department of Biological Chemistry, Baltimore 21201.
authors.forename: J R
authors.initials: JR
authors.lastname: Lakowicz
authors.forename: I
authors.initials: I
authors.lastname: Gryczynski
authors.forename: G
authors.initials: G
authors.lastname: Laczko
authors.forename: W
authors.initials: W
authors.lastname: Wiczk
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D000595:Amino Acid Sequence; D004743:Enkephalin, Leucine / Q000737:chemistry*; D007700:Kinetics; D008969:Molecular Sequence Data; D013050:Spectrometry, Fluorescence; D013696:Temperature; D013816:Thermodynamics; D014443:Tyrosine / Q000737:chemistry*
chemical_list: D000178:Acrylamides; D014443:Tyrosine; D004743:Enkephalin, Leucine