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Challenges in Enzyme Catalysis - Photosystem II and Orotidine Decarboxylase: A Density Functional Theory Treatment
Stockholms universitet.ORCID iD: 0000-0002-1312-1202
2005 (English)Doctoral thesis, comprehensive summary (Other academic)Text
Abstract [en]

Possibly the most fascinating biochemical mechanism remaining to be solved is the formation of oxygen from water in photosystem II. This is a critical part of the photosynthetic reaction that makes solar energy accessible to living organisms.

The present thesis uses quantum chemistry, more specifically the density functional B3LYP, to investigate a mechanism where an oxyl radical bound to manganese is the active species in O-O bond formation. Benchmark calculations on manganese systems confirm that B3LYP can be expected to give accurate results. The effect of the self-interaction error is shown to be limited. Studies of synthetic manganese complexes support the idea of a radical mechanism. A manganese complex with an oxyl radical is active in oxygen formation while manganese-oxo complexes remain inactive. Formation of the O-O bond requires a spin transition but there should be no effect on the rate. Spin transitions are also required in many short-range electron-transfer reactions.

Investigations of the superproficient enzyme orotidine decarboxylase support a mechanism that involves an invariant network of charged amino acids, acting together with at least two mobile water molecules.

Place, publisher, year, edition, pages
Stockholm: Fysikum, Stockholms universitet , 2005. , 77 p.
National Category
Theoretical Chemistry
URN: urn:nbn:se:uu:diva-276494ISBN: 91-7155-057-7OAI: diva2:903197
Available from: 2016-02-15 Created: 2016-02-15 Last updated: 2016-02-15Bibliographically approved

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Lundberg, Marcus
Theoretical Chemistry

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