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Using de novo desig...
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Berry, Bruce W.,1974-Stockholms universitet,Institutionen för biokemi och biofysik
(author)
Using de novo design proteins to explore tyrosine radicals and cation-π interactions
Publisher, publication year, extent ...
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Stockholm :Department of Biochemistry and Biophysics, Stockholm University,2014
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69 s.
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electronicrdacarrier
Numbers
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LIBRIS-ID:oai:DiVA.org:su-102008
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ISBN:9789174478853
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https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-102008URI
Supplementary language notes
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Language:English
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Summary in:English
Part of subdatabase
Classification
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Subject category:vet swepub-contenttype
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Subject category:dok swepub-publicationtype
Notes
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At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.
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Redox cofactors and amino-acid free radicals play important roles in biology. Although many of the same cofactors and amino acids that form these radicals are found across a broad range of biological systems, identical cofactors can have different reduction potentials. The local environment plays a role in defining these redox potentials. An understanding of this local-environment effect can shed more light on how redox chemistry works in nature. Our laboratory has developed a library of model proteins that are well suited to study amino-acid radicals. a3X is a de novo designed protein that is composed of 67 residues. It forms a three-helix bundle connected by two glycine loops. The radical site is located at position 32 on the central a-helix. The a3X protein is designed to be well-folded and thermodynamically stable across a broad pH range. Paper 1 describes the structural and electrochemical characterization of a3Y, a tyrosine variant of a3X. We were able to obtain a unique Faradaic response from Y32 at both low and high pH, using differential pulse voltammetry. In addition, we successfully redesigned α3Y by introducing a histidine in close proximity to Y32, creating a tyrosine/histidine pair. Our goal in creating this pair was to study proton-coupled electron transfer (PCET) in a well-structured and solvent-sequestered protein environment. In paper 2 we illustrated the redox reversibility of Y32 and produced the first ever Pourbaix diagram for a tyrosine radical in a protein. The formal potential of the Y32-O/Y32-OH redox couple was determined to be 918 ± 2 mV vs. the normal hydrogen electrode (NHE) at pH 8.40. While at pH 5.52, the formal potential of the Y32-O/Y32-OH redox couple was recorded at 1.07 V. Papers 3 and 4 utilize a3W to study cation-π interactions. In paper 3, we showed how solvation can affect the strength of these interactions by -0.9 kcal/mol. In Paper 4, we were able to monitor the disruption of the cation-π interaction with the use of high-pressure fluorescence and were able to calculate the interaction energy for a solvent exposed cation-π. The aim of the work described in this thesis was to use model proteins to study tyrosine radicals to gain a broader perspective and better understanding of the versatility of biological electron transfer and to measure cation-π interactions and how they behave in different environments.
Subject headings and genre
Added entries (persons, corporate bodies, meetings, titles ...)
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Tommos, Cecilia,Research Assistant ProfessorUniversity of Pennsylvania, Department of Biochemistry and Biophysics
(thesis advisor)
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Hofer, Anders,Associate ProfessorUmeå university, Department of Medical Biochemistry and Biophysics
(opponent)
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Stockholms universitetInstitutionen för biokemi och biofysik
(creator_code:org_t)
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