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. 1972 Mar;69(3):672–675. doi: 10.1073/pnas.69.3.672

Nature of Oxygen Inhibition of Nitrogenase from Azotobacter vinelandii

Peter P Wong 1, R H Burris 1
PMCID: PMC426532  PMID: 4501581

Abstract

The reduction of nitrogen, acetylene, azide, and cyanide at various oxygen concentrations by nitrogenase from Azotobacter vinelandii was measured with a well-defined system. Oxygen inhibited the reduction of each substrate uncompetitively. The inhibition constants (Ki) were 0.014, 0.023, 0.008, and 0.003 atm of oxygen for reduction of nitrogen, acetylene, azide, and cyanide, respectively. The system used included ATP-generating components, subcellular particles from A. vinelandii with high nitrogenase specific activity, and illuminated spinach chloroplasts plus carriers to supply electrons. Oxygen did not affect the photochemical electron donating system, but it did inhibit nitrogenase-dependent ATP hydrolysis.

Keywords: kinetics, oxygen, uncompetitive inhibition

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Selected References

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