Calcium, dinitrogen fixation and calmodulin in a Nostoc
1991
Onek, L.A. | Lea, P.J. | Smith, R.J.
Four inhibitors of Calmodulin and other calcium binding proteins, have been used to probe the calcium mediated effects upon dinitrogen fixation, heterocyst frequency and the intracellular calcium content of Nostoc 6720. The inhibitors both enhance and depress dinitrogen fixation depending upon their concentration, but do not significantly affect the heterocyst frequency or the intracellular calcium content. The results confirm the presence of two distinct calcium concentration dependent effects; a calcium dependent protection of nitrogenase from O2 and a calcium mediated inhibition of N2 fixation. The inhibitors provide tools to assist the identification of calcium binding proteins involved in the expression of the calcium mediated, physiological effects.
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