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Title: The role of calcium in the metabolism of Gloeocapsa, with particular reference to nitrogen fixation
Author: Hamadi, A.-F. H.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1981
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Cultures of Gloeocapsa rapidly lost their ability to reduce acetylene when incubated with 1 mM-EDTA, either in the light or aerobically in the dark. However, EDTA did not inhibit acetylene reduction by cultures of Gloeocapsa incubated anaerobically in the dark. Among various chloride salts only 5 mM-CaC12 completely prevented this effect of EDTA. EDTA not only affected Gloeocapsa nitrogenase, it also inhibited the growth of Gloeocapsa in medium containing nitrogen (for example NH,+ or N0,-) as well as in medium free of combined nitrogen. Furthermore, EDTA affected various other metabolic reactions in Gloeocapsa, several of which could not be correlated directly with nitrogen fixation. It is concluded that EDTA inhibits nitrogenase by disrupting a Ca2+-dependent mechanism that protects the enzyme from inactivation by 02. The exact nature of this mechanism has not been established, but the most likely candidates are respiratory protection and/or conformational protection, the latter possibly involving, directly or indirectly, intracellular membranes of Gloeocapsa.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available