The article "Time-resolved vibrational spectroscopy detects protein-based intermediates in the photosynthetic oxygen-evolving cycle" appears in PNAS, May 9 2006 edition. Authors include Dr. Bridgette Barry, Ian B. Cooper, Antonio De Riso, Scott H. Brewer, Dung M. Vu, and R. Brian Dyer.

PNAS paper

From "About this issue":

"More states for the photosynthetic complex Understanding the properties of the photosynthetic cycle is important because oxygen production from photosynthesis is responsible for aerobic life on earth. Bridgette Barry et al. report the finding of previously unidentified intermediate states in the oxygen-evolving photosynthesis protein complex. The authors used time-resolved vibrational infrared spectroscopy to measure protein conformation in the photosystem II oxygen-evolving complex as it converts water into free oxygen. The oxygen-evolving complex goes through four photooxidation steps to oxidize water, cycling through five states called Sn, where n denotes the number of oxidizing equivalents in the complex. Barry et al. found that a protein-based intermediate is produced on the microsecond time scale for each photo-induced transition. Measurements revealed states that were hidden from UV and x-ray spectroscopy. A protein-derived conformational change or proton transfer reaction may occur at each S-state transition. According to the authors, their findings may help in the verification of different models for photosynthetic water oxidation. - P.D."

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Commentary

For more information on this research, contact Dr. Bridgette Barry (404-385-6085).