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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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Publication details

The article was received on 25 Oct 2019, accepted on 25 Nov 2019 and first published on 27 Nov 2019


Article type: Edge Article
DOI: 10.1039/C9SC05405G
Chem. Sci., 2020, Advance Article
  • Open access: Creative Commons BY-NC license
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    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, Advance Article , DOI: 10.1039/C9SC05405G

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