A laser flash absorption spectroscopy study of Anabaena sp. PCC 7119 flavodoxin photoreduction by photosystem I particles from spinach.
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 x 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 MgCl2, with maximum values in the 40-80 mM range for NaCl and 4-12 mM for MgCl2. To our knowledge, this is the first time that the kinetics of PSI-dependent flavodoxin photoreduction have been determined.
Medina
M
M
Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, Spain.
Hervás
M
M
Navarro
J A
JA
De la Rosa
M A
MA
Gómez-Moreno
C
C
Tollin
G
G
D000458:Cyanobacteria / Q000737:chemistry*; D004579:Electron Transport; D005418:Flavodoxin / Q000737:chemistry*; D015636:Magnesium Chloride / Q000494:pharmacology; D010084:Oxidation-Reduction; D010782:Photolysis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D045331:Photosystem I Protein Complex; D010944:Plants; D012965:Sodium Chloride / Q000494:pharmacology; D013057:Spectrum Analysis
D005418:Flavodoxin; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D015636:Magnesium Chloride; D012965:Sodium Chloride