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Issue 14, 2016
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Direct measurement of the tryptophan-mediated photocleavage kinetics of a protein disulfide bond

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Abstract

Disulfide cleavage is one of the major causes underlying ultraviolet (UV) light-induced protein damage. While previous studies have provided strong evidence to support the notion that this process is mediated by photo-induced electron transfer from the excited state of an aromatic residue (e.g., tryptophan) to the disulfide bond, many mechanistic details are still lacking. For example, we do not know how quickly this process occurs in a protein environment. Herein, we design an experiment, which uses the unfolding kinetics of a protein as an observable, to directly assess the kinetics and mechanism of photo-induced disulfide cleavage. Our results show that this disulfide bond cleavage event takes place in ∼2 μs via a mechanism involving electron transfer from the triplet state of a tryptophan (Trp) residue to the disulfide bond. Furthermore, we find that one of the photoproducts of this reaction, a Trp-SR adduct, is formed locally, thus preventing the protein from re-cross-linking. Taken together, these findings suggest that a Trp-disulfide pair could be used as a photo-trigger to initiate protein folding dynamics and control the biological activities of disulfide-containing peptides.

Graphical abstract: Direct measurement of the tryptophan-mediated photocleavage kinetics of a protein disulfide bond

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Publication details

The article was received on 06 Feb 2016, accepted on 04 Mar 2016 and first published on 08 Mar 2016


Article type: Paper
DOI: 10.1039/C6CP00865H
Author version available: Download Author version (PDF)
Citation: Phys. Chem. Chem. Phys., 2016,18, 9602-9607
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    Direct measurement of the tryptophan-mediated photocleavage kinetics of a protein disulfide bond

    R. M. Abaskharon and F. Gai, Phys. Chem. Chem. Phys., 2016, 18, 9602
    DOI: 10.1039/C6CP00865H

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