title: Contribution of vitamin K1 to the electron spin polarization in spinach photosystem I.
abstract: The electron spin polarized (ESP) electron paramagnetic resonance (EPR) signal observed in spinach photosystem I (PSI) particles was examined in preparations depleted of vitamin K1 by solvent extraction and following biological reconstitution by the quinone. The ESP EPR signal was not detected in the solvent-extracted PSI sample but was restored upon reconstitution with either protonated or deuterated vitamin K1 under conditions that also restored electron transfer to the terminal PSI acceptors. Reconstitution using deuterated vitamin K1 resulted in a line narrowing of the ESP EPR signal, supporting the conclusion that the ESP EPR signals in the reconstituted samples arise from a radical pair consisting of the oxidized PSI primary donor, P700+, and reduced vitamin K1.
authors.affiliation: Chemistry Division, Argonne National Laboratory, Illinois 60439.
authors.forename: R R
authors.initials: RR
authors.lastname: Rustandi
authors.forename: S W
authors.initials: SW
authors.lastname: Snyder
authors.forename: L L
authors.initials: LL
authors.lastname: Feezel
authors.forename: T J
authors.initials: TJ
authors.lastname: Michalski
authors.forename: J R
authors.initials: JR
authors.lastname: Norris
authors.forename: M C
authors.initials: MC
authors.lastname: Thurnauer
authors.forename: J
authors.initials: J
authors.lastname: Biggins
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D010084:Oxidation-Reduction; D010777:Photochemistry; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism* / Q000528:radiation effects; D045331:Photosystem I Protein Complex; D010837:Vitamin K 1 / Q000378:metabolism*
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010837:Vitamin K 1