Nitrite and Nitric Oxide as Inhibitors of Nitrogenase from Soybean Bacteroids

AUTOR(ES)

Trinchant, Jean-Charles

RESUMO

Nitrite was able to strongly inhibit C2H2 reduction by nitrogenase from soybean bacteroids, whereas H2 evolution was unaffected under the same conditions. NO inhibited both C2H2 reduction and H2 evolution; during C2H2 reduction, sensitivity of nitrogenase to NO was higher than to NO2−, and the Ki values were, respectively, 0.056 and 0.52 mM. Production of NO resulting from a reduction of NO2− by dithionite in nitrogenase incubations was observed. However, the characteristics of inhibitions and the low level of NO generated by nitrite reduction ruled out the suggestion concerning a direct role of NO to explain the inhibitory effect of NO2− on nitrogenase.

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