| Autor: |
Lars H. Eng, Halina Y. Neujahr, Marian T. Stankovich, Dan Li Wang |
| Rok vydání: |
1991 |
| Předmět: |
|
| Zdroj: |
Journal of Electroanalytical Chemistry and Interfacial Electrochemistry. 318:291-307 |
| ISSN: |
0022-0728 |
| DOI: |
10.1016/0022-0728(91)85311-c |
| Popis: |
Direct electron transfer between cytochrome c 3 from Desulfovibrio desulfuricans NCIMB 8372 and electrodes made of different materials was studied using cyclic voltammetry and differential pulse voltammetry. The mid-point potentials of the four oxidation-reduction states were calculated by simulations using two models. The values have been compared with corresponding values from the mediated spectropotentiometric titration. It was found that the electrode material influenced the value of the potentials except for the first reduction step of the cytochrome. With basal plane graphite and glassy carbon, the most negative reduction step was shifted to a value 30 mV more negative than the value from the potentiometric titration experiment. With gold, the shift was only 10 mV and with dipyridyl-modified gold no shift was observed. When NaCl was included in the electrolyte, the potentials of all four steps shifted to values approximately 100 mV more negative in tests with basal plane graphite, glassy carbon and gold electrodes alike. The mid-point potentials of the four hemes were determined from two different simulation models. The mutual conversion of these two series of data is discussed. One of the four hemes is found to be independent of the other hemes. No strong interaction between the remaining hemes is proposed. The binding pattern of the ferri- and ferrocytochrome to anion and cation exchangers suggests that, upon reduction, the isoelectric point changes from pH 9.5–10 to pH 6.5–7. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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