The product(s) of reaction catalyzed by nitrogenase in root nodules...

MECHANISM OF BIOLOGICAL N₂ FIXATION:

It takes place in leguminous plants (Fabaceae) by the symbiotic bacterium Rhizobium, which forms nodules in their roots. N₂ is directly converted into an NH₄⁺ ion, which is used in plant metabolism. Root nodules act as the site for N₂ fixation. It contains all necessary biochemical components like enzyme nitrogenase, leghaemoglobin, that are required in N₂ fixation. Enzyme nitrogenase is a Mo–Fe protein & catalyzes the conversion of atmospheric N₂ to NH₃.

The reaction takes place in two steps:

$( i ) {N}_{2} + 8{e}^{-} + 8{H}^{+} + 16ATP\overset{Nitrogenase}{\to}2N{H}_{3} + {H}_{2} + 16ADP + 16Pi ( ii ) 2N{H}_{3} + {H}_{2} \to 2N{H}_{4}^{+} + 2{e}^{-}$