These two authors contributed equally to this work.
Structural Characterization of a Zinc High-affinity Binding Site in Rhodopsin†
Article first published online: 13 FEB 2009
© 2009 The Authors. Journal Compilation. The American Society of Photobiology
Photochemistry and Photobiology
Volume 85, Issue 2, pages 479–484, March/April 2009
How to Cite
Toledo, D., Cordomí, A., Proietti, M. G., Benfatto, M., Del Valle, L. J., Pérez, J. J., Garriga, P. and Sepulcre, F. (2009), Structural Characterization of a Zinc High-affinity Binding Site in Rhodopsin. Photochemistry and Photobiology, 85: 479–484. doi: 10.1111/j.1751-1097.2008.00529.x
This paper is part of the Proceedings of the 13th International Conference on Retinal Proteins, Barcelona, Spain, 15–19 June 2008.
- Issue published online: 25 FEB 2009
- Article first published online: 13 FEB 2009
- Received 14 August 2008, accepted 24 November 2008
For the first time to our knowledge, X-ray absorption spectroscopy (XAS) has been used to investigate the environment of putative Zn2+ binding sites in rhodopsin. We studied native purified nondeionized rhodopsin without any further addition of Zn2+, as well as with 1.5 mol of Zn2+—as zinc chloride—per mole of protein. Three different binding sites in rhodopsin were considered based on computational chemistry studies, and a quantitative analysis of the XAS signal was performed by fitting the experimental data to their simulated XAS spectra. Our results demonstrate that Zn2+ is intrinsically bound to rhodopsin and are compatible with the existence of an octahedral coordination involving six oxygen atoms in the first shell (average Zn-O distance of 2.08 Å), and with a second coordination shell containing one or two phosphorus or sulfur atoms at an average distance of 2.81 Å.