The mechanism of photosynthetic water splitting

James P. McEvoy, Jose A. Gascon, Victor S. Batista, Gary W Brudvig

Research output: Contribution to journalArticle

108 Citations (Scopus)

Abstract

Oxygenic photosynthesis, which provides the biosphere with most of its chemical energy, uses water as its source of electrons. Water is photochemically oxidized by the protein complex photosystem II (PSII), which is found, along with other proteins of the photosynthetic light reactions, in the thylakoid membranes of cyanobacteria and of green plant chloroplasts. Water splitting is catalyzed by the oxygen-evolving complex (OEC) of PSII, producing dioxygen gas, protons and electrons. O2 is released into the atmosphere, sustaining all aerobic life on earth; product protons are released into the thylakoid lumen, augmenting a proton concentration gradient across the membrane; and photo-energized electrons pass to the rest of the electron-transfer pathway. The OEC contains four manganese ions, one calcium ion and (almost certainly) a chloride ion, but its precise structure and catalytic mechanism remain unclear. In this paper, we develop a chemically complete structure of the OEC and its environment by using molecular mechanics calculations to extend and slightly adjust the recently-obtained X-ray crystallographic model [K. N. Ferreira, T. M. Iverson, K. Maghlaoui, J. Barber and S. Iwata, Science, 2004, 303, 1831-1838]. We discuss our mechanistic hypothesis [J. P. McEvoy and G. W. Brudvig, Phys. Chem. Chem. Phys., 2004, 6, 4754-4763] with reference to this structure and to some important recent experimental results.

Original languageEnglish
Pages (from-to)940-949
Number of pages10
JournalPhotochemical and Photobiological Sciences
Volume4
Issue number12
DOIs
Publication statusPublished - Dec 2005

Fingerprint

water splitting
Electrons
Oxygen
Protons
Thylakoids
Photosystem II Protein Complex
protons
Water
oxygen
Ions
chloroplasts
membranes
proteins
manganese ions
biosphere
chemical energy
electrons
lumens
photosynthesis
sustaining

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Cell Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Biophysics

Cite this

The mechanism of photosynthetic water splitting. / McEvoy, James P.; Gascon, Jose A.; Batista, Victor S.; Brudvig, Gary W.

In: Photochemical and Photobiological Sciences, Vol. 4, No. 12, 12.2005, p. 940-949.

Research output: Contribution to journalArticle

McEvoy, James P. ; Gascon, Jose A. ; Batista, Victor S. ; Brudvig, Gary W. / The mechanism of photosynthetic water splitting. In: Photochemical and Photobiological Sciences. 2005 ; Vol. 4, No. 12. pp. 940-949.
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