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Proton-coupled elec...
Proton-coupled electron transfer of tyrosine oxidation : buffer dependence and parallel mechanisms
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- Irebo, Tania, 1980- (författare)
- Uppsala universitet,Institutionen för fotokemi och molekylärvetenskap
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Reece, Steven Y. (författare)
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- Sjödin, Martin (författare)
- Uppsala universitet,Institutionen för fotokemi och molekylärvetenskap
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Nocera, Daniel G. (författare)
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- Hammarström, Leif (författare)
- Uppsala universitet,Kemisk fysik
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(creator_code:org_t)
- 2007-11-21
- 2007
- Engelska.
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 129:50, s. 15462-15464
- Relaterad länk:
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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
- The proton-coupled electron transfer (PCET) from tyrosine covalently linked to a metal complex has been studied. The reaction was induced by laser flash excitation of the metal complex, and PCET was bidirectional, with electron transfer to the excited or flash-quenched oxidized metal complex and proton transfer to water or added buffers in the solution. We found a competition between three different PCET mechanisms: (1) A concerted PCET with water as the proton acceptor, which indeed shows a pH-dependence as earlier reported (Sjödin, M.; Styring, S.; Åkermark, B.; Sun, L.; Hammarström, L. J. Am. Chem. Soc. 2000, 122, 3932); (2) a stepwise electron transfer-proton transfer (ETPT) that is pH-independent; (3) a buffer-assisted concerted PCET. The relative importance of reaction 2 increases with oxidant strength, while that of reaction 1 increases with pH. At higher buffer concentrations reaction 3 becomes important, and the rate follows the expected first-order dependence on the concentration of the buffer base. Most importantly, the pH-dependence of reaction 1, with a slope of 0.4-0.5 in a plot of log k vs pH, is independent of buffer and cannot be explained by reaction schemes with simple first-order dependencies on [OH-], [H3O+], or buffer species.
Ämnesord
- NATURVETENSKAP -- Kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences (hsv//eng)
Nyckelord
- Chemistry
- Multidisciplinary
- Chemistry
- Kemi
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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