Photoactivation of the photosynthetic reaction center of Blastochloris viridis in the crystalline state.
Photoactivation in crystals of the bacterial reaction center of Blastochloris viridis was investigated by near-infrared spectroscopy. The bleaching of the special pair absorption at 970 nm and the simultaneous rise of the special pair cation absorption at 1300 nm were measured in response to transient irradiation by a HeNe laser over 5 orders of magnitude in laser power. The resulting power-saturation curve can be used to estimate the true extent of photoactivation achieved in a prior time-resolved crystallographic experiment (Baxter et al. Proc. Natl. Acad. Sci. U.S.A. 2004, 101, 5982-5987). The overall extent of photoactivation was 50%, which demonstrates that the time-resolved crystallographic method can be applied to the optically dense reaction center crystals. Measurement of the charge-recombination rate, however, suggests the presence of a long-lived P+ state within the crystal.
Department of Chemistry, University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, USA. rbaxter@alumni.uchicago.edu
Richard H G
RH
Baxter
Elmars
E
Krausz
James R
JR
Norris
D003460:Crystallization; D003461:Crystallography; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000502:physiology / Q000528:radiation effects*; D020560:Proteobacteria / Q000737:chemistry / Q000502:physiology / Q000528:radiation effects*; D019265:Spectroscopy, Near-Infrared
D045322:Photosynthetic Reaction Center Complex Proteins