Electron transfer from cytochrome c to cupredoxins |
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Authors: | Shin-ichi J Takayama Kiyofumi Irie Hulin Tai Takumi Kawahara Shun Hirota Teruhiro Takabe Luis A Alcaraz Antonio Donaire Yasuhiko Yamamoto |
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Institution: | 1. Department of Chemistry, University of Tsukuba, Tsukuba, 305-8571, Japan 2. Department of Physical Chemistry, Kyoto Pharmaceutical University, Yamashina-ku, Kyoto, 607-8414, Japan 3. Graduate School of Materials Science, Nara Institute of Science and Technology (NAIST), Nara, 630-0192, Japan 4. Research Institute, Meijo University, Tempaku-ku, Nagoya, 468-8502, Japan 5. Instituto de Biología Molecular y Celular, Universidad Miguel Hernández de Elche, Edificio Torregaitán, Avda. de la Universidad s/n, 03202, Elche, Alicante, Spain 6. Departamento de Química Inorgánica, Facultad de Química, Universidad de Murcia, Campus Universitario, Apdo. 4021, 30071, Murcia, Spain
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Abstract: | Electron transfer (ET) through and between proteins is a fundamental biological process. The activation energy for an ET reaction
depends upon the Gibbs energy change upon ET (ΔG
0) and the reorganization energy. Here, we characterized ET from Pseudomonas aeruginosa cytochrome c
551 (PA) and its designed mutants to cupredoxins, Silene pratensis plastocyanin (PC) and Acidithiobacillus ferrooxidans rusticyanin (RC), through measurement of pseudo-first-order ET rate constants (k
obs). The influence of the ΔG
0 value for ET from PA to PC or RC on the k
obs value was examined using a series of designed PA proteins exhibiting a variety of E
m values, which afford the ΔG
0 variation range of 58–399 meV. The plots of the k
obs values obtained against the ΔG
0 values for both PA–PC and PA–RC redox pairs could be fitted well with a single Marcus equation. We have shown that the ET
activity of cytochrome c can be controlled by tuning the E
m value of the protein through the substitution of amino acid residues located in hydrophobic-core regions relatively far from
the redox center. These findings provide novel insights into the molecular design of cytochrome c, which could be utilized for controlling its ET activity by means of protein engineering.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Cupredoxin Electron transfer Cytochrome c Marcus theory Redox potential |
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