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Intrachain Contact Dynamics in Unfolded Cytochrome cb_(562)

Bouley Ford, Nicole D. and Shin, Dong-Woo and Gray, Harry B. and Winkler, Jay R. (2013) Intrachain Contact Dynamics in Unfolded Cytochrome cb_(562). Journal of Physical Chemistry B, 117 (42). pp. 13206-13211. ISSN 1520-6106. PMCID PMC3816711. doi:10.1021/jp403234h.

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We have investigated intrachain contact dynamics in unfolded cytochrome cb_(562) by monitoring heme quenching of excited ruthenium photosensitizers covalently bound to residues along the polypeptide. Intrachain diffusion for chemically denatured proteins proceeds on the microsecond time scale with an upper limit of 0.1 μs. The rate constants exhibit a power-law dependence on the number of peptide bonds between the heme and Ru complex. The power-law exponent of −1.5 is consistent with theoretical models for freely jointed Gaussian chains, but its magnitude is smaller than that reported for several synthetic polypeptides. Contact formation within a stable loop was examined in a His63-heme ligated form of the protein under denaturing conditions. Loop formation accelerated contact kinetics for the Ru66 labeling site, owing to reduction in the length of the peptide separating redox sites. For other labeling sites within the stable loop, quenching rates were modestly reduced compared to the open chain polymer.

Item Type:Article
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URLURL TypeDescription DOIArticle CentralArticle
Gray, Harry B.0000-0002-7937-7876
Winkler, Jay R.0000-0002-4453-9716
Additional Information:© 2013 American Chemical Society. Received: April 1, 2013; Revised: August 11, 2013; Published: August 30, 2013. We celebrate Peter Wolynes, our very good friend and collaborator. Our explorations of protein folding dynamics have been greatly enhanced by the many discussions we have had with him over the last 20 years. We thank Lionel Cheruzel, Jeffrey Warren, Maraia Ener, and Katja Luxem for experimental assistance and helpful discussions. Our work was supported by NIH (Grants DK019038 and GM068461) and the Arnold and Mabel Beckman Foundation.
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Arnold and Mabel Beckman FoundationUNSPECIFIED
Issue or Number:42
PubMed Central ID:PMC3816711
Record Number:CaltechAUTHORS:20131204-142946287
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Official Citation:Intrachain Contact Dynamics in Unfolded Cytochrome cb562 Nicole D. Bouley Ford, Dong-Woo Shin, Harry B. Gray, and Jay R. Winkler The Journal of Physical Chemistry B 2013 117 (42), 13206-13211
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42837
Deposited By: Tony Diaz
Deposited On:05 Dec 2013 00:36
Last Modified:10 Nov 2021 16:29

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