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Pourbaix Diagram, P...
Pourbaix Diagram, Proton-Coupled Electron Transfer, and Decay Kinetics of a Protein Tryptophan Radical : Comparing the Redox Properties of W32• and Y32• Generated Inside the Structurally Characterized α3W and α3Y Proteins
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- Glover, Starla (författare)
- Uppsala universitet,Fysikalisk kemi,Univ Penn, Dept Biochem & Biophys, Perelman Sch Med, Philadelphia
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- Tyburski, Robin (författare)
- Uppsala universitet,Fysikalisk kemi
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- Liang, Li (författare)
- Univ Penn, Dept Biochem & Biophys, Perelman Sch Med, Philadelphia
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- Tommos, Cecilia (författare)
- Univ Penn, Dept Biochem & Biophys, Perelman Sch Med, Philadelphia
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- Hammarström, Leif, 1964- (författare)
- Uppsala universitet,Fysikalisk kemi
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(creator_code:org_t)
- 2017-12-19
- 2018
- Engelska.
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 140:1, s. 185-192
- Relaterad länk:
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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
Ämnesord
Stäng
- Protein-based “hole” hopping typically involves spatially arranged redox-active tryptophan or tyrosine residues. Thermodynamic information is scarce for this type of process. The well-structured α3W model protein was studied by protein film square wave voltammetry and transient absorption spectroscopy to obtain a comprehensive thermodynamic and kinetic description of a buried tryptophan residue. A Pourbaix diagram, correlating thermodynamic potentials (E°′) with pH, is reported for W32 in α3W and compared to equivalent data recently presented for Y32 in α3Y (Ravichandran, K. R.; Zong, A. B.; Taguchi, A. T.; Nocera, D. G.; Stubbe, J.; Tommos, C. J. Am. Chem. Soc. 2017, 139, 2994−3004). The α3W Pourbaix diagram displays a pKOX of 3.4, a E°′(W32(N•+/NH)) of 1293 mV, and a E°′(W32(N•/NH); pH 7.0) of 1095 ± 4 mV versus the normal hydrogen electrode. W32(N•/NH) is 109 ± 4 mV more oxidizing than Y32(O•/OH) at pH 5.4–10. In the voltammetry measurements, W32 oxidation–reduction occurs on a time scale of about 4 ms and is coupled to the release and subsequent uptake of one full proton to and from bulk. Kinetic analysis further shows that W32 oxidation likely involves pre-equilibrium electron transfer followed by proton transfer to a water or small water cluster as the primary acceptor. A well-resolved absorption spectrum of W32• is presented, and analysis of decay kinetics show that W32• persists ∼104 times longer than aqueous W• due to significant stabilization by the protein. The redox characteristics of W32 and Y32 are discussed relative to global and local protein properties.
Ämnesord
- NATURVETENSKAP -- Biologi -- Biofysik (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences -- Biophysics (hsv//eng)
- NATURVETENSKAP -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)
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- general trends
- can be extracted from the scattered
- and limited
- information available
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