Ru(bpy)₃-based artificial receptors toward a protein surface: selective binding and efficient photoreduction of cytochrome c

Abstract

The binding properties of a series of Ru(bpy)₃ complexes to cytochrome c are described; these compounds act as selective cytochrome c receptors and one derivatie is shown to be a photodriven modulator of the cytochrome c redox state.

References

1. For example, (a) H. S. Park, Q. Lin and A. D. Hamilton, J. Am. Chem. Soc., 1999, 121, 8; (b) Y. Hamuro, M. C. Calama, H. S. Park and A. D. Hamilton, Angew. Chem., Int. Ed. Engl., 1997, 36, 2680 and references cited therein.
2. I. Hamachi, A. Fujita and T. Kunitake, J. Am. Chem. Soc., 1997, 119, 9096.
3. (a) I. Hamachi, S. Tanaka and S. Shinkai, J. Am. Chem. Soc., 1993, 115, 10458; (b) S. Sakai and T. Sasaki, J. Am. Chem. Soc., 1994, 116, 1587; (c) I. Hamachi, S. Tsukiji, S. Shinkai and S. Oishi, J. Am. Chem. Soc., 1999, 121, 5500; (d) Y.-Z. Hu, S. Tsukiji, S. Shinkai and I. Hamachi, Chem. Lett., 1999, 517.
4. (a) G. R. Newkome, X. Lin and J. K. Young, Synlett, 1992, 53; (b) J. Issberner, F. Vögtle, L. D. Cola and V. Balzani, Chem. Eur. J., 1997, 3, 706; (c) G. R. Newkome, R. Güther, C. N. Moorefield, F. Cardullo, L. Echegoyen, E. Perez-Cordero and H. Luftmann, Angew. Chem., Int. Ed. Engl., 1995, 34, 2023; (d) P. J. Dandliker, F. Diederich, M. Gross, C. B. Knober, A. Louati and E. M. Sanford, Angew. Chem., Int. Ed. Engl., 1994, 33, 1739.
5. This value is almost comparable to that of similar compounds, such as dendritic Ru(bpy)₃ under anaerobic conditions (1940 ns) see ref. 4 (b).
6. (a) P.-A. Albertsson, S. Sasakawa and H. Walter, Nature, 1970, 228, 1329; (b) P. D. Barker, J. L. Butler, P. de Oliveria, H. Allen, O. Hill and N. I. Hunt, Inorg. Chim. Acta, 1996, 252, 71.
7. (a) P. L. Drake, R. T. Hartson, J. McGinnis and A. G. Sykes, Inorg. Chem., 1989, 28, 1361; (b) G. J. Kavarnos and N. J. Turro, Chem. Rev., 1986, 86, 401; (c) I. M. Kolthoff and W. J. Tomsicek, J. Phys. Chem., 1935, 39, 945.
8. Although the redox potentials of 1a–c have not been determined thus far, it was reported that the presence of amide groups at the 4 and 4′ positions of bpy positively shifts the redox potential of both *Ru²⁺/Ru³⁺ and Ru²⁺/Ru³⁺. Still, this ET reaction seems favorable, since the potential shift was reported to be within only 0.3–0.4 V; see V. Skarda, M. J. Cook, A. P. Lewis, G. S. G. McAuliffe, A. J. Thomson and D. J. Robbins, J. Chem. Soc., Perkin Trans. 2, 1984, 1309 Details are now under way in our laboratory.
9. No obvious effect on the photoreduction was seen in the control experiments; (i) in the absence of Ru(bpy)₃ derivatives and (ii) under dark conditions.
10. D. J. Pietrzyk and C. W. Frank, Analytical Chemistry, Academic Press, London, 1974, p. 435.
11. The k_ET between a Ru(bpy)₃, Ru(bpy)₃-based dendrimer and anthraquinone-2,6-disulfonate anion (AQ^2–) were recently obtained by similar titration experiments of lifetimes, i.e. k_ET= 1.2 × 10¹⁰ M^–1 s^–1 for Ru(bpy)₃ and k_ET= 2.7 × 10⁹ M^–1 s^–1 for the Ru(bpy)₃-based dendrimer; see F. Vögtle, M. Plevoets, M. Nieger, G. C. Azzellini, A. Credi, I. D. Cola, V. D. Marchis, M. Venturi and V. Balzani, J. Am. Chem. Soc., 1999, 121, 6290.
12. The emission lifetimes of the Ru complexes gradually become shortened by addition of Cyt-c, but the changes for 1b and 1c are saturated at low concentrations of Cyt-c.