title: The functional sites of chlorophylls in D1 and D2 subunits of photosystem II identified by pulsed EPR.
abstract: The functional site of ChlZ, an auxiliary electron donor to P680+, was determined by pulsed ELDOR applied to a radical pair of YD * and Chlz+ in oriented PS II membranes from spinach. The radical-radical distance was determined to be 29.5 A and its direction was 50 degrees from the membrane normal, indicating that a chlorophyll on the D2 protein is responsible for the EPR Chlz+ signal. Spin polarized ESEEM (Electronin Spin Echo Envelop Modulation) of a 3Chl and QA - radical pair induced by a laser flash was observed in reaction center D1D2Cytb559 complex, in which QA was functionally reconstituted with DBMIB and reduced chemically. QA -ESEEM showed a characteristic oscillating time profile due to dipolar coupling with 3Chl. By fitting with the dipolar interaction parameters, the distance between 3Chl and QA - was determined to be 25.9 A, indicating that the accessory chlorophyll on the D1 protein is responsible for the 3Chl signal.
authors.affiliation: School of Science and Technology, Kwansei Gakuin University, Sanda, Japan. kawamori@ksc.kwansei.ac.jp
authors.forename: A
authors.initials: A
authors.lastname: Kawamori
authors.forename: T-A
authors.initials: TA
authors.lastname: Ono
authors.forename: A
authors.initials: A
authors.lastname: Ishii
authors.forename: S
authors.initials: S
authors.lastname: Nakazawa
authors.forename: H
authors.initials: H
authors.lastname: Hara
authors.forename: T
authors.initials: T
authors.lastname: Tomo
authors.forename: J
authors.initials: J
authors.lastname: Minagawa
authors.forename: R
authors.initials: R
authors.lastname: Bittl
authors.forename: S A
authors.initials: SA
authors.lastname: Dzuba
mesh_terms: D000818:Animals; D016825:Chlamydomonas reinhardtii / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000737:chemistry* / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D004735:Energy Transfer; D017353:Gene Deletion; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D018724:Spinacia oleracea / Q000737:chemistry / Q000378:metabolism*
chemical_list: D045332:Photosystem II Protein Complex; D021122:Protein Subunits; D002734:Chlorophyll