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Activation of tripl...
Activation of triplet dioxygen by glucose oxidase : Spin-orbit coupling in the superoxide ion
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Prabhakar, R. (author)
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Siegbahn, P. E. M. (author)
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Minaev, B. F. (author)
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- Ågren, Hans (author)
- KTH,Bioteknologi
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(creator_code:org_t)
- 2002-03-19
- 2002
- English.
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In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 106:14, s. 3742-3750
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Subject headings
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- Hybrid density functional calculations have been performed for the reductive activation of dioxygen by glucose oxidase, for which recent experiments have shown substantial kinetic O-18 isotope effects but no deuterium isotope effect, The present analysis of the mechanism suggests that this surprising isotope effect is best explained if the rate-determining step is the triplet --> singlet interconversion that follows after the electron transfer and the superoxide ion production. The oxygen isotope effect is rationalized by an analysis of the spin-orbit coupling in the radical pair M.+..O-2(.-), where M is the FADH(2) cofactor. For the electron transfer between the M and O-2, the presence of the protonated His516 plays a crucial role by strongly increasing the electron affinity Of O-2, which makes the electron transfer exothermic and allows it to occur without any barrier. The chemical step where hydrogen peroxide is formed has a computed free-energy barrier of only 6.6 kcal/mol.
Keyword
- photosynthetic algae
- aspergillus-niger
- molecular-oxygen
- biochemistry
- transitions
- energies
- behavior
- spectra
- model
- state
Publication and Content Type
- ref (subject category)
- art (subject category)
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