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          Institute: MPI für bioanorganische Chemie     Collection: MPI für bioanorganische Chemie     Display Documents

ID: 683864.0, MPI für bioanorganische Chemie / MPI für bioanorganische Chemie
Efficiency of photosynthetic water oxidation at ambient and depleted levels of inorganic carbon
Authors:Shevela, Dmitriy; Nöring, Birgit; Koroidov, Sergey; Shutova, Tatiana; Samuelsson, Göran; Messinger, Johannes
Date of Publication (YYYY-MM-DD):2013
Title of Journal:Photosynthesis Research
Journal Abbrev.:Photosynth. Res.
Start Page:401
End Page:412
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Over 40 years ago, Joliot et al. (Photochem Photobiol 10:309-329, 1969) designed and employed an elegant and highly sensitive electrochemical technique capable of measuring O-2 evolved by photosystem II (PSII) in response to trains of single turn-over light flashes. The measurement and analysis of flash-induced oxygen evolution patterns (FIOPs) has since proven to be a powerful method for probing the turnover efficiency of PSII. Stemler et al. (Proc Natl Acad Sci USA 71(12):4679-4683, 1974), in Govindjee's lab, were the first to study the effect of "bicarbonate" on FIOPs by adding the competitive inhibitor acetate. Here, we extend this earlier work by performing FIOPs experiments at various, strictly controlled inorganic carbon (C-i) levels without addition of any inhibitors. For this, we placed a Joliot-type bare platinum electrode inside a N-2-filled glove-box (containing 10-20 ppm CO2) and reduced the C-i concentration simply by washing the samples in C-i-depleted media. FIOPs of spinach thylakoids were recorded either at 20-times reduced levels of C-i or at ambient C-i conditions (390 ppm CO2). Numerical analysis of the FIOPs within an extended Kok model reveals that under C-i-depleted conditions the miss probability is discernibly larger (by 2-3 %) than at ambient conditions, and that the addition of 5 mM HCO3 (-) to the C-i-depleted thylakoids largely restores the original miss parameter. Since a "mild" C-i-depletion procedure was employed, we discuss our data with respect to a possible function of free or weakly bound HCO3 (-) at the water-splitting side of PSII.
Free Keywords:Flash-induced oxygen evolution patterns; S states; An extended Kok model; Hydrogen carbonate (bicarbonate); Photosynthetic water oxidation
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für bioanorganische Chemie
External Affiliations:Shevela, D.; Koroidov, S.; Messinger, J.; Umea Univ, Chem Biol Ctr, Dept Chem, S-90187 Umea, Sweden.Shevela, D.; Shevela, D.; Samuelsson, G.; Umea Univ, Umea Plant Sci Ctr, Dept Plant Physiol, S-90187 Umea, Sweden.
Identifiers:ISI:000326604900028 [ID No:1]
ISSN:0166-8595 [ID No:2]
DOI:10.1007/s11120-013-9875-5 [ID No:3]
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