Iron availability affects the growth of not only phytoplankton, but also sea ice diatoms. Iron availability had a clear effect on the growth rates of Fragilariopsis cylindrus and F. curta. Maximum growth rates were 0.57 d–1 for F. cylindrus and 0.28 d–1 for F. curta; Km (half-saturation growth constant) was 0.51 × 10–12 and 1.3 × 10–12 M for F. cylindrus and F. curta, respectively. For both F. ...

Azotobacter vinelandii flavodoxin II serves as a physiological reductant of nitrogenase, the enzyme system mediating biological nitrogen fixation. Wildtype A. vinelandii flavodoxin II was electrochemically and crystallographically characterized to better understand the molecular basis for this functional role. The redox properties were monitored on surfactant-modified basal plane graphite elect...

The 1H, 15N and 13C backbone and 1H and 13C beta resonance assignments of the long-chain flavodoxin from Azotobacter chroococcum (the 20-kDa nifF product, flavodoxin-2) in its oxidized form were made at pH 6.5 and 30 degrees C using heteronuclear multidimensional NMR spectroscopy. Analysis of the NOE connectivities, together with amide exchange rates, 3JHNH alpha coupling constants and secondar...

The catabolic pathway for flavodoxin has yet to be clarified for any bacterial species. In this study, we found that the flavin mononucleotide in the flavodoxin of Helicobacter pylori is degraded to riboflavin via the phosphomonoesterase activity of class C acid phosphatase. The result is a conversion of holoflavodoxin to apoflavodoxin.

The kinetic properties of the electron-transfer process between reduced Desulfovibrio vulgaris cytochrome c3 and D. vulgaris flavodoxin have been studied by anaerobic stopped-flow techniques. Anaerobic titrations of reduced cytochrome c3 with oxidized flavodoxin show a stoichiometry of 4 mol of flavodoxin required to oxidize the tetraheme cytochrome. Flavodoxin neutral semiquinone and oxidized ...

Assimilatory nitrate reductase was particle-bound in extracts from Azotobacter vinelandii. Nitrate reduction by particle fractions was dependent on NADPH and a particle-bound electron carrier. When the enzyme was solubilized from the particles by treatment with detergents, the particle-bound electron carrier could be substituted by ferredoxin or flavodoxin. Flavodoxin reduced at the expense of ...

The purification, crystallization, and biological activity of flavodoxin is reported. It is a new electron transport protein and has been isolated from extracts of cells of Closfridium pasfeurianum grown on nitrogen gas or ammonia and in an iron-deficient medium. Flavodoxin forms yellow crystals from ammonium sulfate solution, has a molecular weight of 14,600, absorption maxima of the oxidized ...

Helicobacter pylori (Hp) infection affects one-half of the human population and produces a variety of diseases from peptic ulcer to cancer. Current eradication therapies achieve modest success rates (around 70%), resistance to the antibiotics of choice is on the rise, and vaccination has not proved to be successful yet. Using an essential Hp protein, flavodoxin, as target, we identified three l...

Flavodoxin isolated from the blue-green alga, Anmyatis nidulana, crystallizes from ammonium sulfate in space group P2,2,2,, wwith a = 67.08 A, b = 69.24 A and c = 45.55 A. The diffraction patterns extend to a resolution of at least 1.8 A. Reduction of the flavin mononucleotide in the crystalline protein, to either the semi-quinone or fully reduced (hydroquinone) state, results in minimal change...

1. The efficiencies of ferredoxins and flavodoxins from a range of sources as mediators in systems for hydrogen evolution were assessed. 2. In supporting electron transfer from dithionite to hydrogenase of the bacterium Clostridium pasteurianum, highest activity was shown by the ferredoxin from the cyanobacterium Chlorogloeopsis fritschii and flavodoxin from the bacterium Megasphaera elsdenii. ...