Occurrence of ferredoxin‐dependent glutamate synthase in plant cell fraction of soybean root nodules (Glycine max)

Ferredoxin‐dependent glutamate synthase (EC 1.4.7.1) and NADH‐dependent glutamate synthase (EC 1.4.1.14) have been identified in the plant cells of soybean nodules. Ferredoxin‐dependent glutamate synthase is 2‐fold more active than NADH‐dependent enzyme in vitro. Ferredoxin‐dependent glutamate synthase cross‐reacts with IgG against ferredoxin‐dependent glutamate synthase of rice green leaves, whereas NADH‐dependent glutamate synthase does not recognize the IgG, indicating that there are two distinct enzyme proteins. Ferredoxin‐dependent glutamate synthase is composed of polypeptide chain(s) of 165 kDa and has a high affinity to spinach leaf ferredoxin as an electron carrier.