title: Studies on electron donation to photosystem I sites by exogenous donors in Spirulina thylakoids.
abstract: The kinetic parameters of different sites of electron donation to photosystem I (PS I) were evaluated in Spirulina platensis thylakoids. Reduced 2,6-dichlorophenolindophenol (DCIPH2) exhibited two sites of electron donation, with apparent K(m) values of 8 and 40 microM each. The corresponding value for reduced N-tetramethyl-p-phenylenediamine (TMPDH2) and diaminodurene (DADH2) which donate electrons at a single site to PS I were 103 and 48 microM, respectively. The electron donation by these three exogenous donors were differentially inhibited by KCN (70 mM) affecting the apparent K(m) and Rmax values to varying extent. This cyanide inhibition of PS I catalyzed electron transport suggests the presence of plastocyanin in the photosynthetic electron transport chain of Spirulina platensis.
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: B K
authors.initials: BK
authors.lastname: Kolli
authors.forename: J F
authors.initials: JF
authors.lastname: Sah
authors.forename: P
authors.initials: P
authors.lastname: Mohanty
mesh_terms: D015086:2,6-Dichloroindophenol / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D000458:Cyanobacteria / Q000378:metabolism*; D004579:Electron Transport / Q000187:drug effects; D007202:Indicators and Reagents / Q000378:metabolism; D007700:Kinetics; D010101:Oxygen Consumption / Q000187:drug effects; D010655:Phenylenediamines / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D010970:Plastocyanin / Q000378:metabolism; D011190:Potassium Cyanide / Q000494:pharmacology; D013053:Spectrophotometry; D013772:Tetramethylphenylenediamine / Q000378:metabolism
chemical_list: D007202:Indicators and Reagents; D010655:Phenylenediamines; D045322:Photosynthetic Reaction Center Complex Proteins; D002734:Chlorophyll; C005158:diaminodurene; D010970:Plastocyanin; D015086:2,6-Dichloroindophenol; D011190:Potassium Cyanide; D013772:Tetramethylphenylenediamine; D000077194:Chlorophyll A