title: Incoherent manipulation of the photoactive yellow protein photocycle with dispersed pump-dump-probe spectroscopy.
abstract: Photoactive yellow protein is the protein responsible for initiating the "blue-light vision" of Halorhodospira halophila. The dynamical processes responsible for triggering the photoactive yellow protein photocycle have been disentangled with the use of a novel application of dispersed ultrafast pump-dump-probe spectroscopy, where the photocycle can be started and interrupted with appropriately tuned and timed laser pulses. This "incoherent" manipulation of the photocycle allows for the detailed spectroscopic investigation of the underlying photocycle dynamics and the construction of a fully self-consistent dynamical model. This model requires three kinetically distinct excited-state intermediates, two (ground-state) photocycle intermediates, I(0) and pR, and a ground-state intermediate through which the protein, after unsuccessful attempts at initiating the photocycle, returns to the equilibrium ground state. Also observed is a previously unknown two-photon ionization channel that generates a radical and an ejected electron into the protein environment. This second excitation pathway evolves simultaneously with the pathway containing the one-photon photocycle intermediates.
authors.affiliation: Faculty of Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands. dslarsen@nat.vu.nl
authors.forename: Delmar S
authors.initials: DS
authors.lastname: Larsen
authors.forename: Ivo H M
authors.initials: IH
authors.lastname: van Stokkum
authors.forename: Mikas
authors.initials: M
authors.lastname: Vengris
authors.forename: Michael A
authors.initials: MA
authors.lastname: van Der Horst
authors.forename: Frank L
authors.initials: FL
authors.lastname: de Weerd
authors.forename: Klaas J
authors.initials: KJ
authors.lastname: Hellingwerf
authors.forename: Rienk
authors.initials: R
authors.lastname: van Grondelle
mesh_terms: D000465:Algorithms; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D055592:Biophysical Phenomena; D001703:Biophysics; D004583:Electrons; D004926:Escherichia coli / Q000378:metabolism; D020607:Halorhodospira halophila / Q000378:metabolism; D007477:Ions; D007700:Kinetics; D008027:Light; D015233:Models, Statistical; D008962:Models, Theoretical; D017785:Photons; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000378:metabolism; D012984:Software; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry / Q000379:methods*; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D007477:Ions; D020283:Photoreceptors, Microbial; C050162:photoactive yellow protein, Bacteria