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Electrochemical and...
Electrochemical and Structural Properties of a Protein System Designed To Generate Tyrosine Pourbaix Diagrams
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Martinez-Rivera, Melissa C. (author)
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- Berry, Bruce W. (author)
- Stockholms universitet,Institutionen för biokemi och biofysik,University of Pennsylvania, USA
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Valentine, Kathleen G. (author)
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- Westerlund, Kristina (author)
- Stockholms universitet,Institutionen för biokemi och biofysik
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- Hay, Sam (author)
- Stockholms universitet,Institutionen för biokemi och biofysik
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- Tommos, Cecilia (author)
- Stockholms universitet,Institutionen för biokemi och biofysik,University of Pennsylvania, USA
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(creator_code:org_t)
- 2011-10-19
- 2011
- English.
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 133:44, s. 17786-17795
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https://europepmc.or...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
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- This report describes a model protein specifically tailored to electrochemically study the reduction potential of protein tyrosine radicals as a function of pH. The model system is based on the 67-residue alpha(3)Y three-helix bundle, alpha(3)Y contains a single buried tyrosine at position 32 and displays structural properties inherent to a protein. The present report presents differential pulse voltammograms obtained from alpha(3)Y at both:acidic (pH 5.6) and alkaline (pH 8.3) Conditions. The. observed Faradaic. response is uniquely associated. with Y32, as shown by site-directed mutagenesis. This is the first time voltammetry is successfully applied to detect a redox-active tyrosine residing in a structured protein environment. Tyrosine is a proton coupled electron transfer cofactor making voltammetry-based pH titrations a central experimental approach. A second set of experiments was performed to demonstrate that pH-dependent studies can be conducted on the redox-active tyrosine without introducing large-scale structural changes in the protein scaffold alpha(3)Y was re-engineered-with the specific aim to place the imidazole group of a histidine close to the Y32 phenol ring alpha(3)Y-K29H and alpha(3)Y-K36H each contain a histidine residue whose protonation perturbs the fluorescence of Y32. We show that these variants are stable and well-folded proteins whose helical: content, tertiary structure, solution aggregation state, and solvent-sequestered position of Y32 remain pH insensitive across a range of at least 3-4 pH units. These results confirm that the local environment of Y32 can be altered and the resulting radical site studied by voltammetry over a broad pH range without interference from long-range structural effects.
Subject headings
- NATURVETENSKAP -- Biologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences (hsv//eng)
Keyword
- Biochemistry
- biokemi
Publication and Content Type
- ref (subject category)
- art (subject category)
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