Journal article · Preprint article
Dynamic ionic strength effects in fast bimolecular electron transfer between a redox metalloprotein of high electrostatic charge and an inorganic reaction partner
The ionic strength dependence of the bimolecular electron transfer (ET) reaction between Clostridium pasteurianum rubredoxin(III) and photochemically generated [Ru(bpy)_3]^+ has been investigated. The reaction is fast and close to the diffusion-controlled limit. Dynamic ionic strength effects on all kinetics parameters (work terms, driving force, and reorganization free energy) have been incorporated in the data analysis; the effects on the intermolecular work terms are large and dominate in the driving force region close to the activationless limit.
The variation in ET rate constant over the 0.005−2.0 M ionic strength range is quantitatively consistent with the high negative charge (−9e where e is the unit electric charge) and size (crystallographic radius ≈ 12 Å) of rubredoxin(III). If low ionic strength (0.005−0.01 M) data are omitted, the variation in rates suggests a somewhat smaller charge on the protein (−4e to −5e). © 2000 American Chemical Society. Received: April 27, 2000; In Final Form: September 28, 2000. Publication Date (Web): November 10, 2000. We thank D.
M. Kurtz, Jr., and M. K. Eidsness for protein samples and helpful discussions, and I. J. Dmochowski for the p-MDMA sample. T.J.J. thanks A. Tezcan for assistance with the laser spectroscopic measurements. This work was supported by the Technical University of Denmark, the Danish Technical Science Research Council, the National Institutes of Health (DK19038, Beckman Institute), and the Russian Foundation for Basic Research (A.
N. Frumkin Institute).
Language: | English |
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Publisher: | American Chemical Society |
Year: | 2000 |
Pages: | 11556-11562 |
ISSN: | 15205207 and 15206106 |
Types: | Journal article and Preprint article |
DOI: | 10.1021/jp001624u |