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Electrochemical and...
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Martinez-Rivera, Melissa C.
(författare)
Electrochemical and Structural Properties of a Protein System Designed To Generate Tyrosine Pourbaix Diagrams
- Artikel/kapitelEngelska2011
Förlag, utgivningsår, omfång ...
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2011-10-19
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American Chemical Society (ACS),2011
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printrdacarrier
Nummerbeteckningar
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LIBRIS-ID:oai:DiVA.org:su-69903
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https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-69903URI
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https://doi.org/10.1021/ja206876hDOI
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Språk:engelska
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Sammanfattning på:engelska
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Ämneskategori:ref swepub-contenttype
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Ämneskategori:art swepub-publicationtype
Anmärkningar
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authorCount :6
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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.
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Berry, Bruce W.Stockholms universitet,Institutionen för biokemi och biofysik,University of Pennsylvania, USA(Swepub:su)bbruc
(författare)
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Valentine, Kathleen G.
(författare)
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Westerlund, KristinaStockholms universitet,Institutionen för biokemi och biofysik
(författare)
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Hay, SamStockholms universitet,Institutionen för biokemi och biofysik
(författare)
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Tommos, CeciliaStockholms universitet,Institutionen för biokemi och biofysik,University of Pennsylvania, USA
(författare)
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Stockholms universitetInstitutionen för biokemi och biofysik
(creator_code:org_t)
Sammanhörande titlar
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Ingår i:Journal of the American Chemical Society: American Chemical Society (ACS)133:44, s. 17786-177950002-78631520-5126
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