title: Effect of nitrogenase components from mutant and wild-type strains of Azotobacter on the dilution effect of nitrogenase.
abstract: Nitrogenase activity exhibits a dilution effect. Evidence is presented that the reason for the dilution effect is that one of the component proteins of nitrogenase is limiting in preparations of this enzyme. The limiting component appears to be the non-haem-iron-containing protein (also called fraction II, iron protein, azoferredoxin), which is equivalent to the enhancement factor for nitrogenase activity present in extracts of nitrogenaseless mutant 22R1. A mathematical function of specific activity is described that is useful in describing nitrogenase. It takes into account the dilution effect and the exponential nature of the relationship between nitrogenase activity and enzyme protein concentration.
mesh_terms: D001395:Azotobacter / Q000201:enzymology*; D001426:Bacterial Proteins / Q000302:isolation & purification; D002848:Chromatography, DEAE-Cellulose; D007501:Iron / Q000032:analysis; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism; D010088:Oxidoreductases / Q000302:isolation & purification / Q000378:metabolism*; D014461:Ultracentrifugation
chemical_list: D001426:Bacterial Proteins; D007501:Iron; D010088:Oxidoreductases; D009584:Nitrogen