title: Spectroscopic evidence for a redox-controlled proton gate at tyrosine D in Photosystem II.
abstract: Tyrosine D (TyrD) is one of two well-studied redox active tyrosines in Photosystem II. TyrD shows redox kinetics much slower than that of its homologue, TyrZ, and is normally present as a stable deprotonated radical (TyrD(•)). We have used time-resolved continuous wave electron paramagnetic resonance and electron spin echo envelope modulation spectroscopy to show that deuterium exchangeable protons can access TyrD on a time scale that is much faster (50-100 times) than that previously observed. The time of H/D exchange is strongly dependent on the redox state of TyrD. This finding can be related to a change in position of a water molecule close to TyrD.
authors.affiliation: Molecular Biomimetics, Department of Chemistry-Ångström Laboratory, Uppsala University , P.O. Box 523, SE-751 20 Uppsala, Sweden.
authors.forename: Johannes
authors.initials: J
authors.lastname: Sjöholm
authors.forename: Fikret
authors.initials: F
authors.lastname: Mamedov
authors.forename: Stenbjörn
authors.initials: S
authors.lastname: Styring
mesh_terms: D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D006860:Hydrogen Bonding; D007700:Kinetics; D010084:Oxidation-Reduction; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D011522:Protons; D014443:Tyrosine / Q000737:chemistry*
chemical_list: D045332:Photosystem II Protein Complex; D011522:Protons; D014443:Tyrosine