Photosynthetic oxygen evolution: H/D isotope effects and the coupling between electron and proton transfer during transitions S-2 double right arrow S-3 and S-3 double right arrow S-4->S-0

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dc.contributor.authorBogershausen, O
dc.contributor.authorHaumann, M
dc.contributor.authorJunge, W
dc.date.accessioned2021-12-23T15:57:46Z-
dc.date.available2021-12-23T15:57:46Z-
dc.date.issued1996
dc.identifier.issn00059021
dc.identifier.urihttps://osnascholar.ub.uni-osnabrueck.de/handle/unios/3117-
dc.description95th Annual Meeting of the Deutsche-Bunsen-Gesellschaft-fur-Physikalische-Chemie on Primary Processes of Photosynthesis, JENA, GERMANY, MAY 16-18, 1996
dc.description.abstractThe oxygen evolving complex (OEC) of photosystem II (PS II) incorporates a tetra Mn-cluster, tyrosine (Y-Z) and probably one histidine residue (X) as redox cofactors. Four quanta of light drive the OEC through the increasingly oxidized states S-0 double right arrow S-1 double right arrow S-2 double right arrow S-3 double right arrow S-4 to yield O-2 during S-4-->S-0. It has been speculated that some oxidized cofactor abstracts hydrogen from bound water. This implies that its oxidoreduction is electroneutral and linked to its deprotonation. To identify such steps we investigated the rates of electron transfer and proton release as function of the D2O/H2O ratio, the pH, and the temperature in thylakoids and PS II core particles. Upon oxidation of X on S-2 double right arrow S-3, a rise of the pH from 5 to 8 increased the rate of the electron transfer to Y-Z by a factor of 2,5 and substitution of D2O for H2O gave an isotopic ratio of 2.1. Contrastingly, during all other transitions, including the O-2-evolving step S-4-->S-0, the electron transfer rate was much less sensitive to these parameters (factors of less than or equal to 1.4). These results suggest a kinetical steering role of proton transfer only during S-2 double right arrow S-3. We propose that X(.) (His(.)?) serves as a hydrogen acceptor for bound water during S-4-->S-0.
dc.language.isoen
dc.publisherVCH PUBLISHERS INC
dc.relation.ispartofBERICHTE DER BUNSEN-GESELLSCHAFT-PHYSICAL CHEMISTRY CHEMICAL PHYSICS
dc.subjectChemistry
dc.subjectChemistry, Physical
dc.subjectEVOLVING COMPLEX
dc.subjectHISTIDINE OXIDATION
dc.subjectisotope effects
dc.subjectKOK CYCLE
dc.subjectMANGANESE
dc.subjectphotochemistry
dc.subjectPHOTOSYSTEM-II PARTICLES
dc.subjectradicals
dc.subjectREDOX TRANSITIONS
dc.subjectSPECTROSCOPY
dc.subjectspectroscopy, ultraviolet
dc.subjectSPLITTING ENZYME-SYSTEM
dc.subjectTYROSINE Y-Z
dc.subjectWATER OXIDATION
dc.titlePhotosynthetic oxygen evolution: H/D isotope effects and the coupling between electron and proton transfer during transitions S-2 double right arrow S-3 and S-3 double right arrow S-4->S-0
dc.typeconference paper
dc.identifier.isiISI:A1996WB83300009
dc.description.volume100
dc.description.issue12
dc.description.startpage1987
dc.description.endpage1992
dc.contributor.researcheridA-7087-2013
dc.publisher.place303 NW 12TH AVE, DEERFIELD BEACH, FL 33442-1788
dcterms.isPartOf.abbreviationBer. Bunsen-Ges. Phys. Chem. Chem. Phys.
crisitem.author.deptFB 05 - Biologie/Chemie-
crisitem.author.deptidfb05-
crisitem.author.parentorgUniversität Osnabrück-
crisitem.author.netidJuWo587-
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