title: Directionality of electron transfer in cyanobacterial photosystem I at 298 and 77K.
abstract: Electron transfer processes in cyanobacterial photosystem I particles from Synechocystis sp. PCC 6803 with a high potential naphthoquinone (2,3-dichloro-1,4-naphthoquinone) incorporated into the A1 binding site have been studied at 298 and 77K using time-resolved visible and infrared difference spectroscopy. The high potential naphthoquinone inhibits electron transfer past A1, and biphasic P700(+)A1(-) radical pair recombination is observed. The two phases are assigned to P700(+)A1B(-) and P700(+)A1A(-) recombination. Analyses of the transient absorption changes indicate that the ratio of A- and B-branch electron transfer is 95:5 at 77 K and 77:23 at 298 K.
authors.affiliation: Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Makita
authors.affiliation: Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Hastings
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D004579:Electron Transport; D009154:Mutation; D009285:Naphthoquinones / Q000378:metabolism; D045331:Photosystem I Protein Complex / Q000235:genetics / Q000378:metabolism*; D013053:Spectrophotometry; D046939:Synechocystis / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors; D010837:Vitamin K 1 / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D009285:Naphthoquinones; D045331:Photosystem I Protein Complex; D002734:Chlorophyll; C001785:chlorophyll P 700; D010837:Vitamin K 1; C007332:dichlone
keywords: A(1); Dichloronaphthoquinone; Electron transfer; Photosynthesis; Photosystem I; Phylloquinone; Time-resolved spectroscopy