Abstract
The present work describes the results of a study aimed at identifying candidate cation binding sites on the extracellular region of bacteriorhodopsin, including a site near the retinal pocket. The approach used is a combined effort involving computational chemistry methods (computation of cation affinity maps and molecular dynamics) together with the Extended X-Ray Absorption Fine Structure (EXAFS) technique to obtain relevant information about the local structure of the protein in the neighborhood of Mn2+ ions in different affinity binding sites. The results permit the identification of a high-affinity binding site where the ion is coordinated simultaneously to Asp212- and Asp85-. Comparison of EXAFS data of the wild type protein with the quadruple mutant E9Q/E74Q/E194Q/E204Q at pH 7.0 and 10.0 demonstrate that extracellular glutamic acid residues are involved in cation binding. © 2007 Wiley-Liss, Inc.
Original language | English |
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Pages (from-to) | 360-374 |
Journal | Proteins: Structure, Function and Genetics |
Volume | 67 |
DOIs | |
Publication status | Published - 1 May 2007 |
Keywords
- Bacteriorhodopsin
- Mn K-edge
- Mn-EXAFS
- Mn-XANES
- Proton pumping
- Quick EXAFS