ISSN:
1432-072X
Keywords:
Anabaena
;
Biochemical properties
;
Flavodoxin
;
Nitrogenase
;
Photosystem-I electron transport
;
Spectral characteristics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Flavodoxin has been isolated and purified from cultures of the cyanobacterium Anabaena cultivated in a low-iron medium. This flavoprotein has a molecular weight of 20,000 and contains 1 molecule of flavin mononucleotide per mol of protein. Various biochemical characteristics are reported including amino-acid composition, isoelectric point and the fluorescence properties of the apoprotein. The extinction coefficients and isosbestic points were determined for the oxidized and semiquinone forms of flavodoxin. The electron paramagnetic resonance spectrum of the semiquinone exhibited a spectral linewidth of 23 G, which is typical for a neutral flavoprotein semiquinone. Kinetic measurements give a rate constant of 9.6×107 (M-1 min-1) for the reduction of flavodoxin in the photosynthetic electron-transport chain by the photosystem I and 6.6×106 for the reaction in which flavodoxin is reduced by ferredoxin-NADP+ oxidoreductase. The Michaelis constant for electron donation to nitrogenase by reduced flavodoxin is 8.5 μM.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00425156
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