Mechanism and energy diagram for O-O bond formation in the oxygen-evolving complex in photosystem II. Export

@article{citeulike:1922808, abstract = {The recent finding of a transition state with a significantly lower barrier than previously found, has made the mechanism for O-O bond formation in photosystem II much clearer. The full mechanism can be described in the following way. Electrons and protons are ejected from the oxygen-evolving complex (OEC) in an alternating fashion, avoiding unnecessary build-up of charge. The S0-S1 and S1-S2 transitions are quite exergonic, while the S2-S3 transition is only weakly exergonic. The strong endergonic S3-S4 transition is a key step in the mechanism in which an oxygen radical is produced, held by the dangling manganese outside the Mn3Ca cube. The O-O bond formation in the S4-state occurs by an attack of the oxygen radical on a bridging oxo ligand in the cube. The mechanism explains the presence of both a cube with bridging oxo ligands and a dangling manganese. Optimal orbital overlap puts further constraints on the structure of the OEC. An alternating spin alignment is necessary for a low barrier. The computed rate-limiting barrier of 14.7kcalmol-1 is in good agreement with experiments.}, address = {Department of Biochemistry and Biophysics, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden.}, author = {Siegbahn, Per E M E.}, citeulike-article-id = {1922808}, citeulike-linkout-0 = {http://dx.doi.org/10.1098/rstb.2007.2218}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/17971331}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=17971331}, day = {30}, doi = {10.1098/rstb.2007.2218}, issn = {0962-8436}, journal = {Philos Trans R Soc Lond B Biol Sci}, keywords = {mn, mn\_enzyme, oec, psii}, month = {October}, posted-at = {2007-11-15 15:17:24}, priority = {2}, title = {Mechanism and energy diagram for O-O bond formation in the oxygen-evolving complex in photosystem II.}, url = {http://dx.doi.org/10.1098/rstb.2007.2218}, year = {2007} }

TY - JOUR ID - citeulike:1922808 L3 - citeulike-article-id:1922808 N2 - The recent finding of a transition state with a significantly lower barrier than previously found, has made the mechanism for O-O bond formation in photosystem II much clearer. The full mechanism can be described in the following way. Electrons and protons are ejected from the oxygen-evolving complex (OEC) in an alternating fashion, avoiding unnecessary build-up of charge. The S0-S1 and S1-S2 transitions are quite exergonic, while the S2-S3 transition is only weakly exergonic. The strong endergonic S3-S4 transition is a key step in the mechanism in which an oxygen radical is produced, held by the dangling manganese outside the Mn3Ca cube. The O-O bond formation in the S4-state occurs by an attack of the oxygen radical on a bridging oxo ligand in the cube. The mechanism explains the presence of both a cube with bridging oxo ligands and a dangling manganese. Optimal orbital overlap puts further constraints on the structure of the OEC. An alternating spin alignment is necessary for a low barrier. The computed rate-limiting barrier of 14.7kcalmol-1 is in good agreement with experiments. JF - Philos Trans R Soc Lond B Biol Sci SN - 0962-8436 AD - Department of Biochemistry and Biophysics, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden. TI - Mechanism and energy diagram for O-O bond formation in the oxygen-evolving complex in photosystem II. KW - mn KW - mn_enzyme KW - oec KW - psii AU - Siegbahn, Per E M PY - 2007/10/30/ UR - http://dx.doi.org/10.1098/rstb.2007.2218 ER -