Nitrogenase Activity in Cell-Free Extracts of the Blue-Green Alga, Anabaena cylindrica
AUTOR(ES)
Smith, R. V.
RESUMO
Cell-free extracts with high nitrogenase activity were prepared by sonic oscillation and French press treatment from the blue-gree alga Anabaena cylindrica. Extracts were prepared from cells grown on a 95% N2–5% CO2 gas mixture followed by a period of nitrogen starvation under an atmosphere of 95% argon–5% CO2. No increase in the specific activity of extracts was achieved by breaking heterocysts. Activity (assayed by acetylene reduction) was found to be dependent on adenosine triphosphate (ATP), an ATP-generating system, and a low-potential reductant. Na2S2O2 employed as reductant supports higher rates of nitrogenase activity than reduced ferredoxin. The activity is associated with a small-particle fraction that can be sedimented by ultracentrifugation. In contrast to the particulate nitrogenase of Azotobacter, which is stable in air, the A. cylindrica nitrogenase is an oxygen sensitive as nitrogenase prepared from anaerobic bacteria.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=248518Documentos Relacionados
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