A thin-film electrochemical study of the 'blue' copper proteins, auracyanin A and auracyanin B, from the photosynthetic bacterium Chloroflexus aurantiacus: the reduction potential as a function of pH
| Autor: | Fabiola M Selvaraj, Michael J Honeychurch, Alan M. Bond, Robert E. Blankenship, Melissa Bunin Rooney, Hans C. Freeman |
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| Rok vydání: | 2003 |
| Předmět: |
biology
Standard hydrogen electrode Copper protein Chemistry Chloroflexus aurantiacus Analytical chemistry Hydrogen-Ion Concentration biology.organism_classification Electrochemistry Photosynthetic bacterium Biochemistry Chlorobi Inorganic Chemistry Electron transfer Bacterial Proteins Azurin Metalloproteins Protein film voltammetry Thin film Oxidation-Reduction Copper |
| Zdroj: | JBIC Journal of Biological Inorganic Chemistry. 8:306-317 |
| ISSN: | 1432-1327 0949-8257 |
| DOI: | 10.1007/s00775-002-0416-5 |
| Popis: | The reversible formal potentials \(E_{\rm f}^0 \) of auracyanin A and auracyanin B, two closely related "blue" copper proteins from the photosynthetic bacterium Chloroflexus aurantiacus, have been determined by protein film voltammetry in the range 4≤pH≤9. At pH 7 in 0.1 M NaCl, the values of \(E_{\rm f}^0 \) for auracyanin A and auracyanin B are 205±7 mV and 215±7 mV, respectively, versus the standard hydrogen electrode. In both cases there is a smooth but non-sigmoidal change in \(E_{\rm f}^0 \) from ~190 mV at pH 9 to ~240 mV at pH 4. The small changes in \(E_{\rm f}^0 \) as a function of pH indicate that auracyanin A and auracyanin B differ from those "blue" copper proteins in which the Cu site in the reduced (CuI) state switches to a redox-inhibited form at low pH. For auracyanin A, the results obtained by protein film voltammetry are closely similar to those obtained by the conventional spectroelectrochemical method. The findings are discussed in relation to the putative role of auracyanin in biological electron transfer. |
| Databáze: | OpenAIRE |
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