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Issue 3, 2020
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Single electron transfer events and dynamical heterogeneity in the small protein azurin from Pseudomonas aeruginosa

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Abstract

Monitoring the fluorescence of single-dye-labeled azurin molecules, we observed the reaction of azurin with hexacyanoferrate under controlled redox potential yielding data on the timing of individual (forward and backward) electron transfer (ET) events. Change-point analysis of the time traces demonstrates significant fluctuations of ET rates and of mid-point potential E0. These fluctuations are a signature of dynamical heterogeneity, here observed on a 14 kDa protein, the smallest to date. By correlating changes in forward and backward reaction rates we found that 6% of the observed change events could be explained by a change in midpoint potential, while for 25% a change of the donor–acceptor coupling could explain the data. The remaining 69% are driven by variations in complex association constants or structural changes that cause forward and back ET rates to vary independently. Thus, the observed spread in individual ET rates could be related in a unique way to variations in molecular parameters. The relevance for the understanding of metabolic processes is briefly discussed.

Graphical abstract: Single electron transfer events and dynamical heterogeneity in the small protein azurin from Pseudomonas aeruginosa

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Supplementary files

Article information


Submitted
25 Oct 2019
Accepted
25 Nov 2019
First published
27 Nov 2019

This article is Open Access
All publication charges for this article have been paid for by the Royal Society of Chemistry

Chem. Sci., 2020,11, 763-771
Article type
Edge Article

Single electron transfer events and dynamical heterogeneity in the small protein azurin from Pseudomonas aeruginosa

B. Pradhan, C. Engelhard, S. Van Mulken, X. Miao, G. W. Canters and M. Orrit, Chem. Sci., 2020, 11, 763
DOI: 10.1039/C9SC05405G

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