Probing the turnover efficiency of photosystem II membrane fragments with different electron acceptors

详细信息    查看全文

• 作者：Dmitriy Shevela ; ¹ ; ^{dmitry.shevela@uis.no} ; Johannes Messinger ; ^{johannes.messinger@chem.umu.se}
• 关键词：MIMS ; membrane-inlet mass spectrometry ; PSII ; photosystem II ; OEC ; oxygen-evolving complex ; PPBQ ; 2-phenyl-p-benzoquinone ; DCBQ ; 2 ; 5-Dichloro-p-benzoquinone ; FeCy ; K3[Fe(CN)6] ; PQ ; plastoquinone
• 刊名：Biochimica et Biophysica Acta (BBA)/Bioenergetics
• 出版年：2012
• 出版时间：August, 2012
• 年：2012
• 卷：1817
• 期：8
• 页码：1208-1212
• 全文大小：361 K

文摘

In this study we employ isotope ratio membrane-inlet mass spectrometry to probe the turnover efficiency of photosystem II (PSII) membrane fragments isolated from spinach at flash frequencies between 1 Hz and 50 Hz in the presence of the commonly used exogenous electron acceptors potassium ferricyanide(III) (FeCy), 2,5-dichloro-p-benzoquinone (DCBQ), and 2-phenyl-p-benzoquinone (PPBQ). The data obtained clearly indicate that among the tested acceptors PPBQ is the best at high flash frequencies. If present at high enough concentration, the PSII turnover efficiency is unaffected by flash frequency of up to 30 Hz, and at 40 Hz and 50 Hz only a slight decrease by about 5-7 % is observed. In contrast, drastic reductions of the O₂ yields by about 40 % and 65 % were found at 50 Hz for DCBQ and FeCy, respectively. Comparison with literature data reveals that PPBQ accepts electrons from Q_A^{?/sup> in PSII membrane fragments with similar efficiency as plastoquinone in intact cells. Our data also confirm that at high flashing rates O₂ evolution is limited by the reactions on the electron-acceptor side of PSII. The relevance of these data to the evolutionary development of the water-splitting complex in PSII and with regard to the potential of artificial water-splitting catalysts is discussed. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.}