Sensitively probing the cofactor redox species and photo-induced electron transfer of wild-type and pheophytin-replaced photosynthetic proteins reconstituted in self-assembled monolayers |
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Authors: | Jingjing Xu Yidong Lu Baohong Liu Chunhe Xu Jilie Kong |
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Institution: | (1) Chemistry Department and Institutes of Biomedical Sciences, Fudan University, Shanghai, 200433, People’s Republic of China;(2) Shanghai Institute of Plant Physiology and Ecology, Shanghai Institute for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, People’s Republic of China;(3) Department of Chemistry, Fudan University, Shanghai, 200433, People’s Republic of China |
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Abstract: | An ultrathin, ordered, and packed protein film, consisting of the 2-mercaptoacetic acid (MAA), polydimethyldiallylammonium
chloride (PDDA), and wild-type (WT) photosynthetic reaction center (RC; termed as WT-RC) or its pheophytin (Phe)-replaced
counterpart (termed as Phe-RC), was fabricated by self-assembling technique onto gold electrode for facilitating the electron
transfer (ET) between RC and the electrode surface. Near-infrared (NIR)-visible (Vis) absorption and fluorescence (FL) emission
spectra revealed the influence of pigment substitution on the cofactors arrangement and excitation relaxation of the proteins,
respectively. Square wave voltammetry (SWV) and photoelectric tests were employed to systematically address the differences
between the WT-RC films and mutant ones on the direct and photo-induced ET. The electrochemical results demonstrated that
ET initiated by the oxidation of the primary donor (P) was obviously slowed down, and the formed P+ had more population as well as more positive redox potential in the Phe-RC films compared with those in the WT ones. The
photoelectrochemical results displayed the dramatically enhanced photoelectric performances of the mutant ones, further suggesting
the slow-down formation of final charge-separated state in Phe-RC. The functionalized protein films introduced in this paper
provided an efficient approach to sensitively probe the redox cofactors and ET differences resulting from only minor changes
in pigment arrangement in the pigment–protein complex. The favored ET process observed for the membrane proteins RC was potentially
valuable for a deep understanding of the multi-step biological ET process and development of versatile bioelectronic devices. |
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Keywords: | Photosynthetic reaction center Self-assembled monolayers Electron transfer Square wave voltammetry Photocurrent |
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