Electron Flow through Nitrotyrosinate in Pseudomonas aeruginosa Azurin
Abstract
We have designed ruthenium-modified Pseudomonas aeruginosa azurins that incorporate 3-nitrotyrosine (NO_(2)YOH) between Ru(2,2′-bipyridine)_2(imidazole)(histidine) and Cu redox centers in electron transfer (ET) pathways. We investigated the structures and reactivities of three different systems: RuH107NO_(2)YOH109, RuH124NO_(2)YOH122, and RuH126NO_(2)YOH122. RuH107NO_(2)YOH109, unlabeled H124NO_(2)YOH122, and unlabeled H126NO_(2)YOH122 were structurally characterized. The pKa's of NO_(2)YOH at positions 122 and 109 are 7.2 and 6.0, respectively. Reduction potentials of 3-nitrotyrosinate (NO_(2)YO^–)-modified azurins were estimated from cyclic and differential pulse voltammetry data: oxidation of NO_(2)YO^(–)122 occurs near 1.1 versus NHE; oxidation of NO_(2)YO^(–)109 is near 1.2 V. Our analysis of transient optical spectroscopic experiments indicates that hopping via NO_(2)YO^– enhances Cu^I oxidation rates over single-step ET by factors of 32 (RuH107NO_(2)YO^(–)109), 46 (RuH126NO_(2)YO^(–)122), and 13 (RuH124NO_(2)YO^(–)122).
Additional Information
© 2013 American Chemical Society. Received: April 15, 2013; published: July 16, 2013. Our work was supported by NIH (DK019038 to H.B.G. and J.R.W.; GM095037 to J.J.W.), an NSF Center for Chemical Innovation (Powering the Planet, CHE-0947829), and the Arnold and Mabel Beckman Foundation. We also acknowledge the Gordon and Betty Moore Foundation and the Sanofi- Aventis Bioengineering Research Program for their support of the Molecular Observatory facilities at the California Institute of Technology. X-ray crystallography data was collected at the Stanford Synchrotron Radiation Lightsource (SSRL), a Directorate of the SLAC National Accelerator Laboratory and an Office of Science User Facility operated for the U.S. Department of Energy, Office of Molecular Biology Program and Environmental Research, and by the National Institutes of Health, National Center for Research Resources, Biomedical Technology Program (P41RR001209), and the National Institute of General Medical Sciences.Attached Files
Accepted Version - nihms-506875.pdf
Supplemental Material - ja403734n_si_001.pdf
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Additional details
- PMCID
- PMC3839300
- Eprint ID
- 42069
- Resolver ID
- CaltechAUTHORS:20131025-104510564
- NIH
- DK019038
- NIH
- GM095037
- NSF
- CHE-0947829
- Arnold and Mabel Beckman Foundation
- Sanofi-Aventis Bioengineering Research Program
- Created
-
2013-10-28Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- CCI Solar Fuels