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Biomedical subjects

M C Evans

Publications and source records attributed to M C Evans.

At least 163 records · Page 9Linked to original sources
PubMed1971

Nitrogenase activity in cell-free extracts of the blue-green alga, Anabaena cylindrica.

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% N(2)-5% CO(2) gas mixture followed by a period of nitrogen starvation under an atmosphere of 95% argon-5% CO(2). 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. Na(2)S(2)O(2) 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.

Acetylene↗
PubMed1968

The stoicheiometry of electron transfer by bacterial and plant ferredoxins.

1. The number of electrons carried by ferredoxins from spinach, the blue-green alga Anacystis nidulans, the anaerobic bacterium Clostridium welchii and the photosynthetic bacterium Chromatium was determined. 2. Ferredoxins were reduced by illuminated chloroplasts, and the stoicheiometry of the reoxidation in the dark of the ferredoxins by NADP and benzyl viologen was measured. 3. Spinach and A. nidulans ferredoxins were found to be one-electron carriers, and Cl. welchii and Chromatium ferredoxins were two-electron carriers.

Chloroplasts↗