Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published April 6, 2011 | Supplemental Material + Accepted Version
Journal Article Open

Electron Transfer Reactivity of Type Zero Pseudomonas aeruginosa Azurin

Abstract

Type zero copper is a hard-ligand analogue of the classical type 1 or blue site in copper proteins that function as electron transfer (ET) agents in photosynthesis and other biological processes. The EPR spectroscopic features of type zero Cu^(II) are very similar to those of blue copper, although lacking the deep blue color, due to the absence of thiolate ligation. We have measured the rates of intramolecular ET from the pulse radiolytically generated C3−C26 disulfide radical anion to the Cu^(II) in both type zero C112D/M121L and type 2 C112D Pseudomonas aeruginosa azurins in pH 7.0 aqueous solutions between 8 and 45 °C. We also have obtained rate/temperature (10−30 °C) profiles for ET reactions between these mutants and the wild-type azurin. Analysis of the rates and activation parameters for both intramolecular and intermolecular ET reactions indicates that the type zero copper reorganization energy falls in a range (0.9−1.1 eV) slightly above that for type 1 (0.7−0.8 eV), but substantially smaller than that for type 2 (>2 eV), consistent with XAS and EXAFS data that reveal minimal type zero site reorientation during redox cycling.

Additional Information

© 2011 American Chemical Society. Published In Issue April 06, 2011; Article ASAP March 15, 2011; Received: October 28, 2010. We thank Jay Winkler and Bruce Brunschwig for helpful discussions, Serena DeBeer for XAS advice, Matt Sazinsky for use of an anaerobic chamber, and Eran Gilad for valuable assistance with PR system operations. We also acknowledge several suggestions from a reviewer. Our research was supported by NIH DK019038 and Stanford GCEP. X-ray absorption spectroscopic experiments were carried out at the Stanford Synchrotron Radiation Lightsource, a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. The SSRL Structural Molecular Biology Program is supported by the Department of Energy, Office of Biological and Environmental Research, and by the National Institutes of Health, National Center for Research Resources, Biomedical Technology Program.

Attached Files

Accepted Version - nihms281097.pdf

Supplemental Material - ja1093919_si_001.pdf

Files

ja1093919_si_001.pdf
Files (4.2 MB)
Name Size Download all
md5:af9bd9c9dfc503352d3ee09f60c11d9c
2.3 MB Preview Download
md5:644dc36d6d4dd0feabb32decdef7964c
1.9 MB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 23, 2023