Factors Controlling the Redox Potential of ZnCe6 in an Engineered Bacterioferritin Photochemical 'Reaction Centre'

Abdullah Mahboob, Serguei Vassiliev, Prashanth K. Poddutoori, Art van der Est, Doug Bruce

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Photosystem II (PSII) of photosynthesis has the unique ability to photochemically oxidize water. Recently an engineered bacterioferritin photochemical 'reaction centre' (BFR-RC) using a zinc chlorin pigment (ZnCe6) in place of its native heme has been shown to photo-oxidize bound manganese ions through a tyrosine residue, thus mimicking two of the key reactions on the electron donor side of PSII. To understand the mechanism of tyrosine oxidation in BFR-RCs, and explore the possibility of water oxidation in such a system we have built an atomic-level model of the BFR-RC using ONIOM methodology. We studied the influence of axial ligands and carboxyl groups on the oxidation potential of ZnCe6 using DFT theory, and finally calculated the shift of the redox potential of ZnCe6 in the BFR-RC protein using the multi-conformational molecular mechanics-Poisson-Boltzmann approach. According to our calculations, the redox potential for the first oxidation of ZnCe6 in the BRF-RC protein is only 0.57 V, too low to oxidize tyrosine. We suggest that the observed tyrosine oxidation in BRF-RC could be driven by the ZnCe6 di-cation. In order to increase the efficiency of tyrosine oxidation, and ultimately oxidize water, the first potential of ZnCe6 would have to attain a value in excess of 0.8 V. We discuss the possibilities for modifying the BFR-RC to achieve this goal.

Original languageEnglish
Article numbere68421
JournalPLoS One
Volume8
Issue number7
DOIs
Publication statusPublished - Jul 30 2013
Externally publishedYes

Fingerprint

photochemical reactions
Photochemical reactions
redox potential
Oxidation-Reduction
Tyrosine
tyrosine
oxidation
Oxidation
Photosystem II Protein Complex
Water
photosystem II
chlorins
Photosynthesis
Manganese
Molecular mechanics
Mechanics
Heme
water
heme
Cations

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Factors Controlling the Redox Potential of ZnCe6 in an Engineered Bacterioferritin Photochemical 'Reaction Centre'. / Mahboob, Abdullah; Vassiliev, Serguei; Poddutoori, Prashanth K.; van der Est, Art; Bruce, Doug.

In: PLoS One, Vol. 8, No. 7, e68421, 30.07.2013.

Research output: Contribution to journalArticle

Mahboob, Abdullah ; Vassiliev, Serguei ; Poddutoori, Prashanth K. ; van der Est, Art ; Bruce, Doug. / Factors Controlling the Redox Potential of ZnCe6 in an Engineered Bacterioferritin Photochemical 'Reaction Centre'. In: PLoS One. 2013 ; Vol. 8, No. 7.
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