Artículo
Abstract:
The electrochemical behaviour of ubiquinone 10 (UQ10) adsorbed on mercury in contact with aqueous electrolytes has been investigated at coverages smaller than a monolayer. Stability regions, acid-base ionisation constants and standard potentials for redox equilibria between conjugate stable species were determined and reaction mechanisms proposed. The standard potential for the ubiquinone/ubihydroquinone couple obtained was 0.276 V vs. SCE (-0.138 at pH 7). The values of pKa obtained for the two acid-base dissociation equilibria for the ubihydroquinone, 12 and 13.6, are higher than those predicted from the Hammett equation and lower than the value obtained in a low-relative-permittivity medium (80% w/w ethanol). The ubisemiquinone ion redical has been found to be stable at pH > 13.6 with a disproportionation constant of 0.4. The corresponding constant for the protonated radical was estimated to be 1014, showing the high instability of this form. This fact, together with kinetic considerations, suggests that for pH values lower than 12 the redox chemistry proceeds via dismutation. Two-phase transitions for the reduced and oxidised forms were observed.
Registro:
| Documento: | Artículo |
| Título: | Redox properties of ubiquinon (UQ10) adsorbed on a mercury electrode |
| Autor: | Gordillo, G.J.; Schiffrin, D.J. |
| Filiación: | Chemistry Department, Donnan and Robert Robinson Laboratories, University of Liverpool, P.O. Box 147, Liverpool, L69 3BX, United Kingdom Departamento de Quimica Inorgánica, Analítica y Química Fisica, Universidad de Buenos Aires, Ciudad Universitaria, 1824 Buenos Aires, Argentina |
| Año: | 1994 |
| Volumen: | 90 |
| Número: | 13 |
| Página de inicio: | 1913 |
| Página de fin: | 1922 |
| DOI: | http://dx.doi.org/10.1039/FT9949001913 |
| Título revista: | Journal of the Chemical Society, Faraday Transactions |
| ISSN: | 09565000 |
| Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09565000_v90_n13_p1913_Gordillo |
Referencias:
- Ondarroa, M., Quinn, P.J., (1986) Biochem. J., 240, p. 325
- Ondarroa, M., Quinn, P.J., (1986) Eur. J. Biochem., 155, p. 353
- Regan, C.I., Heron, C., (1978) Biochem. J., 178, p. 783
- Ohnishi, T., Salerno, J.C., Blum, H., Leigh, J.S., Ingledew, W.I., (1977) Bioenergetics of Membranes, p. 209. , L. Parker, G. C. Papageorgiou, A. Trebst, Elsevier, Amsterdam
- Urban, P.F., Klingenberg, M., (1969) Eur. J. Biochem., 9, p. 519
- Crane, F.L., Barr, R., (1985) Coenzyme Q, p. 1. , G. Lenaz, Wiley, Chichester
- Morrison, L.E., Schelhorn, J.E., Cotton, T.M., Bering, C.L., Loach, P.A., (1982) Function of Quinones in Energy Conserving Systems, p. 35. , B. L. Trumpower, Academic Press, New York
- Ksenzhek, O.S., Petrova, S.A., Kolodyazhy, M.V., (1982) Bioelectrochem. Bioenerg., 9, p. 167
- Schrebler, R.S., Arratia, A., Sanchez, S., Haun, M., Duram, N., (1990) Bioelectrochem. Bioenerg., 23, p. 81
- Takehara, K., Ide, Y., (1991) Bioelectrochem. Bioenerg., 26, p. 297
- Nelson, A., Benton, A., (1986) J. Electroanal. Chem., 202, p. 253
- Leermakers, F.A.M., Nelson, A., (1990) J. Electroanal. Chem., 278, p. 53
- Nelson, A., Leermakers, F.A.M., (1990) J. Electroanal. Chem., 278, p. 73
- Trumpower, B.L., (1981) J. Bioenerg. Biomembr., 13, p. 1
- Damaskin, B.B., Petrii, O.A., Batrakov, V.V., (1971) Adsorption of Organic Compounds on Electrodes, , Plenum Press, New York
- Bard, A.J., Faulkner, L.R., (1980) Electrochemical Methods, p. 521. , Wiley, New York
- Laviron, E., (1974) J. Electroanal. Chem., 52, p. 395
- Brown, A.P., Anson, F.C., (1977) Anal. Chem., 49, p. 1589
- Plichon, V., Laviron, E., (1976) J. Electroanal. Chem., 71, p. 143
- Barlin, G.B., Perrin, D.D., (1966) Quart. Rev., 20, p. 75
- Parsons, R., (1959) Handbook of Electrochemical Constants, , Butter-worths, London
- Patel, K.B., Willson, R.L., (1973) J. Chem. Soc., Faraday Trans. 1, 69, p. 814
- Land, E.J., Swallow, A.J., (1970) J. Biol. Chem., 245, p. 1890
- Laviron, E., (1979) J. Electroanal. Chem., 101, p. 19
- Willson, R.L., (1971) J. Chem. Soc., Faraday Trans. 1, 67, p. 3020
- Rao, P.S., Hayon, E., (1973) J. Chem. Phys., 77, p. 2274
- Janssen, L.H.M., van Til, A.L., van Duijneveldt, F.B., (1992) Bioelectrochem. Bioenerg., 27, p. 161
- Baxendale, J.H., Hardy, H.R., (1953) Trans. Faraday Soc., 49, p. 1140
- Serejeant, E.P., Bempsey, B., (1979) Ionisation Constants of Organic Acids in Aqueous Solution, , IUPAC Chemical Data Series No. 23, Pergamon Press, Oxford
Citas:
---------- APA ----------
Gordillo, G.J. & Schiffrin, D.J. (1994) . Redox properties of ubiquinon (UQ10) adsorbed on a mercury electrode. Journal of the Chemical Society, Faraday Transactions, 90(13), 1913-1922.http://dx.doi.org/10.1039/FT9949001913
---------- CHICAGO ----------
Gordillo, G.J., Schiffrin, D.J. "Redox properties of ubiquinon (UQ10) adsorbed on a mercury electrode" . Journal of the Chemical Society, Faraday Transactions 90, no. 13 (1994) : 1913-1922.http://dx.doi.org/10.1039/FT9949001913
---------- MLA ----------
Gordillo, G.J., Schiffrin, D.J. "Redox properties of ubiquinon (UQ10) adsorbed on a mercury electrode" . Journal of the Chemical Society, Faraday Transactions, vol. 90, no. 13, 1994, pp. 1913-1922.http://dx.doi.org/10.1039/FT9949001913
---------- VANCOUVER ----------
Gordillo, G.J., Schiffrin, D.J. Redox properties of ubiquinon (UQ10) adsorbed on a mercury electrode. 1994;90(13):1913-1922.http://dx.doi.org/10.1039/FT9949001913
