title: Time-resolved fluorescence of the bacteriophage T4 capsid protein gp23.
abstract: The time-resolved fluorescence properties of the bacteriophage T4 capsid protein gp23 are investigated. The structural characteristics of this protein are largely unknown and can be probed by recording time-resolved and decay-associated fluorescence spectra and intensity decay curves using a 200 ps-gated intensified CCD-camera. Spectral and decay data are recorded simultaneously, which makes data acquisition fast compared to time-correlated single-photon counting. A red-shift of the emission maximum within the first nanosecond of decay is observed, which can be explained by the different decay-associated spectra of fluorescence lifetimes of the protein in combination with dipolar relaxation. In addition, iodide quenching experiments are performed, to study the degree of exposure of the various tryptophan residues. A model for the origin of the observed lifetimes of 0.032 +/- 0.003, 0.39 +/- 0.06, 2.1 +/- 0.1 and 6.8 +/- 0.8 ns is presented: the 32 ps lifetime can be assigned to the emission of a buried tryptophan residue, the 0.4 and 2.1 ns lifetimes to two partly buried residues, and the 6.8 ns lifetime to a single tryptophan outside the bulk of the folded gp23.
authors.affiliation: Department of Analytical Chemistry and Applied Spectroscopy, Faculty of Sciences, Vrije Universiteit, Laser Centre VU, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
authors.forename: Aike
authors.initials: A
authors.lastname: Stortelder
authors.forename: Joost B
authors.initials: JB
authors.lastname: Buijs
authors.forename: Jaap
authors.initials: J
authors.lastname: Bulthuis
authors.forename: Saskia M
authors.initials: SM
authors.lastname: van der Vies
authors.forename: Cees
authors.initials: C
authors.lastname: Gooijer
authors.forename: Gert
authors.initials: G
authors.lastname: van der Zwan
mesh_terms: D036022:Capsid Proteins / Q000737:chemistry* / Q000378:metabolism*; D005453:Fluorescence; D007454:Iodides; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D036022:Capsid Proteins; D007454:Iodides; C064517:gp23 protein, Bacteriophage T4