Incoherent manipulation of the photoactive yellow protein photocycle with dispersed pump-dump-probe spectroscopy.
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.
Larsen
Delmar S
DS
Faculty of Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands. dslarsen@nat.vu.nl
van Stokkum
Ivo H M
IH
Vengris
Mikas
M
van Der Horst
Michael A
MA
de Weerd
Frank L
FL
Hellingwerf
Klaas J
KJ
van Grondelle
Rienk
R
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
D001426:Bacterial Proteins; D007477:Ions; D020283:Photoreceptors, Microbial; C050162:photoactive yellow protein, Bacteria