Influence of pigment substitution on the electrochemical properties ofRhodobacter sphaeroides 601 reaction centers |
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Authors: | Yonglong Zou Jiequan Zhao Zhilong Chen Jilie Kong Xiaohua Zeng Chunhe Xu |
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Institution: | (1) Shanghai Institute of Plant Physiology, Shanghai Institutes of Life Science, Chinese Academy of Sciences, 200032 Shanghai, China;(2) Department of Chemistry, Fudan University, 200433 Shanghai, China;(3) Faculty of Naval Medicine, Second Military Medical University, 200433 Shanghai, China |
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Abstract: | With the help of pigment substitution, self-assembled monolayer film and square wave voltammetry, the influence of pigment
substitution on the electrochemical properties ofRhodobacter sphaeroides 601 reaction centers was investigated. Results showed that the charge separation could also be driven by externally electric
field, similar to the primary photochemical reaction in purple bacterial reaction center. On the surface of Au electrode,
a self-assembled monolayer film (the RC-PDDA-DMSA film) was made up of 2,3-dimercaptosuccinic acid (DMSA), poly-dimethyldiallylammonium
chloride (PDDA) and reaction center (RC). When square wave voltammetry was used to study the RC-PDDA-DMSA film, four redox
pairs in the photochemical reaction of RC were observed by changing frequency. With nonlinear fitting, the standard potential
of P/P+ and the corresponding electrode reaction rate constant were determined to be 0.522 V and 13.04 S-1, respectively. It was found that the redox peak at −0.02 V changed greatly when bacteriopheophytin was substituted by plant
pheophytin in the reaction center. Further studies indicated that this change resulted from the decrease in electron transfer
rate between Bphe-/Bphe (Phe-/Phe) and QA
-/QA after pigment substitution. After investigations of spectra and electrochemical properties of different RCs and comparisons
of different function groups of pigments, it was indicated that the phytyl tail, similar to other substituted groups of pheophytin,
affected the efficiencies of pigment substitution. |
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Keywords: | pheophytin substitution monolayer film square wave voltammetry primary photochemical reaction redox pair phytyl |
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