title: Reaction pattern of photosystem II: oxidative water cleavage and protein flexibility.
abstract: This short communication addresses three topics of photosynthetic water cleavage in Photosystem II (PS II): (a) effect of protonation in the acidic range on the extent of the 'fast' ns kinetics of P680+. reduction by YZ, (b) mechanism of O-O bond formation and (c) role of protein flexibility in the functional integrity of PS II. Based on measurements of light-induced absorption changes and quasielastic neutron scattering in combination with mechanistic considerations, evidence is presented for the protein acting as a functionally active constituent of the water cleavage machinery, in particular, for directed local proton transfer. A specific flexibility emerging above a threshold of about 230 K is an indispensable prerequisite for oxygen evolution and plastoquinol formation.
authors.affiliation: Max-Volmer-Laboratorium für Biophysikalische Chemie, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Kühn
authors.forename: Jörg
authors.initials: J
authors.lastname: Pieper
authors.forename: Olga
authors.initials: O
authors.lastname: Kaminskaya
authors.forename: Hann-Jörg
authors.initials: HJ
authors.lastname: Eckert
authors.forename: Ruep E
authors.initials: RE
authors.lastname: Lechner
authors.forename: Vladimir
authors.initials: V
authors.lastname: Shuvalov
authors.forename: Gernot
authors.initials: G
authors.lastname: Renger
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D000458:Cyanobacteria / Q000737:chemistry / Q000378:metabolism; D008027:Light; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D011522:Protons; D018724:Spinacia oleracea / Q000737:chemistry / Q000378:metabolism; D013696:Temperature; D014867:Water / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D011522:Protons; D014867:Water; D010100:Oxygen