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A laser flash absorption spectroscopy study of Anabaena sp. PCC 7119 flavodoxin photoreduction by photosystem I particles from spinach
Author(s) -
Medina Milagros,
Hervás Manuel,
Navarro José A.,
De la Rosa Miguel A.,
Gómez-Moreno Carlos,
Tollin Gordon
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)81200-6
Subject(s) - flavodoxin , p700 , photosystem i , electron transfer , chemistry , spinach , kinetics , reaction rate constant , photochemistry , absorption (acoustics) , photosystem ii , spectroscopy , analytical chemistry (journal) , photosynthesis , materials science , ferredoxin , chromatography , biochemistry , physics , enzyme , quantum mechanics , composite material
Electron transfer from P700 in photosystem I (PSI) particles from spinach to Anabaena sp. PCC 7119 flavodoxin has been studied using laser flash absorption spectroscopy. A non‐linear protein concentration dependence of the rate constants was obtained, suggesting a two‐step mechanism involving complex formation ( k =3.6 × 10 7 M −1 · s −1 ) followed by intracomplex electron transfer ( k =270 s −1 ). The observed rate constants had a biphasic dependence on the concentrations of NaCl or MgCl 2 with maximum values in the 40–80 mM range for NaCl and 4–12 mM for MgCl 2 . To our knowledge, this is the first time that the kinetics of PSI‐dependent flavodoxin photoreduction have been determined.