DC Field | Value | Language |
dc.contributor.author | Haumann, M | |
dc.contributor.author | Mulkidjanian, A | |
dc.contributor.author | Junge, W | |
dc.date.accessioned | 2021-12-23T16:10:41Z | - |
dc.date.available | 2021-12-23T16:10:41Z | - |
dc.date.issued | 1999 | |
dc.identifier.issn | 00062960 | |
dc.identifier.uri | https://osnascholar.ub.uni-osnabrueck.de/handle/unios/9346 | - |
dc.description.abstract | Tn oxygen-evolving photosystem II (PSII), a tyrosine residue, D1Tyr161 (Y-Z), serves as the intermediate electron carrier between the catalytic Mn cluster and the photochemically active chlorophyll moiety P-680 A more direct catalytic role of Y-Z, as a hydrogen abstractor from bound water, has been postulated. That Y-Z(ox) appears as a neutral (i.e. deprotonated) radical, Y-Z(.), in EPR studies is compatible with this notion. Data based on electrochromic absorption transients, however, are conflicting because they indicate that the phenolic proton remains on or near to Y-Z(ox). In Mn-depleted PSII the electron transfer between Y-Z and P-680(+) can be almost as fast as in oxygen-evolving material, however, only at alkaline pH. With an apparent pK of about 7 the fast reaction is suppressed and converted into an about 100-fold slower one which dominates at acid PH In the present work we investigated the optical difference spectra attributable to the transition Y-Z --> Y-Z(ox) as function of the pH. We scanned the UV and VIS range and used Mn-depleted PSII core particles and also oxygen-evolving ones. Comparing these spectra with published in vitro and in vivo spectra of phenolic compounds, we arrived at the following conclusions: In oxygen-evolving PSII Y-Z resembles a hydrogen-bonded tyrosinate, Y-Z((-))... H(+). B. The phenolic proton is shifted toward a base B already in the reduced state and even more so in the oxidized state. The retention of the phenolic proton in a hydrogen-bonded network gives rise to a positive net charge in the immediate vicinity of the neutral radical Y-Z(.). It may be favorable both for the very rapid reduction by Y-Z of P-680(+) and for electron (not hydrogen) abstraction by Y-Z(.) from the Mn-water cluster. | |
dc.language.iso | en | |
dc.publisher | AMER CHEMICAL SOC | |
dc.relation.ispartof | BIOCHEMISTRY | |
dc.subject | ABSORBANCE DIFFERENCE SPECTRA | |
dc.subject | AMINO-ACID-RESIDUES | |
dc.subject | Biochemistry & Molecular Biology | |
dc.subject | CHARGE RECOMBINATION | |
dc.subject | ELECTRON-PARAMAGNETIC-RESONANCE | |
dc.subject | MANGANESE CLUSTER | |
dc.subject | PHOTOSYNTHETIC WATER OXIDATION | |
dc.subject | PROTON-TRANSFER | |
dc.subject | REDOX-ACTIVE TYROSINE | |
dc.subject | REDUCTION KINETICS | |
dc.subject | SITE-DIRECTED MUTAGENESIS | |
dc.title | Tyrosine-Z in oxygen-evolving photosystem II: A hydrogen-bonded tyrosinate | |
dc.type | review | |
dc.identifier.doi | 10.1021/bi981557i | |
dc.identifier.isi | ISI:000078836500013 | |
dc.description.volume | 38 | |
dc.description.issue | 4 | |
dc.description.startpage | 1258 | |
dc.description.endpage | 1267 | |
dc.contributor.orcid | 0000-0001-5844-3064 | |
dc.contributor.researcherid | AAH-3608-2021 | |
dc.contributor.researcherid | J-8086-2013 | |
dc.contributor.researcherid | A-7087-2013 | |
dc.publisher.place | 1155 16TH ST, NW, WASHINGTON, DC 20036 USA | |
dcterms.isPartOf.abbreviation | Biochemistry | |
crisitem.author.dept | Universität Osnabrück | - |
crisitem.author.dept | FB 05 - Biologie/Chemie | - |
crisitem.author.deptid | fb05 | - |
crisitem.author.orcid | 0000-0001-5844-3064 | - |
crisitem.author.parentorg | Universität Osnabrück | - |
crisitem.author.netid | MuAr001 | - |
crisitem.author.netid | JuWo587 | - |