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Main Title: An unusual role for the phytyl chains in the photoprotection of the chlorophylls bound to Water-Soluble Chlorophyll-binding Proteins
Author(s): Agostini, Alessandro
Palm, Daniel M.
Schmitt, Franz-Josef
Albertini, Marco
Valentin, Marilena Di
Paulsen, Harald
Carbonera, Donatella
Type: Article
Abstract: Water-Soluble Chlorophyll Proteins (WSCPs) from Brassicaceae are non-photosynthetic proteins which tetramerize upon binding four chlorophyll (Chl) molecules. The bound Chls are highly photostable, despite the lack of bound carotenoids known, in Chl-containing photosynthetic proteins, to act as singlet oxygen and Chl triplet (3Chl) quenchers. Although the physiological function of WSCPs is still unclear, it is likely to be related to their biochemical stability and their resistance to photodegradation. To get insight into the origin of this photostability, the properties of the 3Chl generated in WSCPs upon illumination were investigated. We found that, unlike the excited singlet states, which are excitonic states, the triplet state is localized on a single Chl molecule. Moreover, the lifetime of the 3Chl generated in WSCPs is comparable to that observed in other Chl-containing systems and is reduced in presence of oxygen. In contrast to previous observations, we found that WSCP actually photosensitizes singlet oxygen with an efficiency comparable to that of Chl in organic solvent. We demonstrated that the observed resistance to photooxidation depends on the conformation of the phytyl moieties, which in WSCP are interposed between the rings of Chl dimers, hindering the access of singlet oxygen to the oxidizable sites of the pigments.
Subject(s): water-soluble chlorophyll proteins
Issue Date: 7-Aug-2017
Date Available: 19-Nov-2020
Language Code: en
DDC Class: 500 Naturwissenschaften und Mathematik
Journal Title: Scientific Reports
Publisher: Nature Publishing Group
Volume: 7
Article Number: 7504
Publisher DOI: 10.1038/s41598-017-07874-6
EISSN: 2045-2322
TU Affiliation(s): Fak. 2 Mathematik und Naturwissenschaften » Inst. Chemie » FG Bioenergetik
Appears in Collections:Technische Universit├Ąt Berlin » Publications

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