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- Title
Structural Characterization of a Zinc High-affinity Binding Site in Rhodopsin.
- Authors
Toledo, Darwin; Cordomí, Arnau; Proietti, Maria Grazia; Benfatto, Maurizio; del Valle, Luis J.; Pérez, Juan J.; Garriga, Pere; Sepulcre, Francesc
- Abstract
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.
- Subjects
RHODOPSIN; X-ray spectroscopy; LIGAND binding (Biochemistry); ATOMS; ZINC chloride; PHOTOCHEMICAL research
- Publication
Photochemistry & Photobiology, 2009, Vol 85, Issue 2, p479
- ISSN
0031-8655
- Publication type
Article
- DOI
10.1111/j.1751-1097.2008.00529.x