Enzymes of ammonia assimilation in Rhizobium leguminosarum bacteroids

The activities of the following enzymes were studied in connection with dinitrogen fixation in pea bacteroids: glutamine synthetase(L-glutamate: ammonia ligase (ADP-forming)(EC 6.3.1.2)(GS); glutamate dehydrogenase (NADP+)(L-glutamate: NADP+ oxidoreductase (deaminating)(EC 1.4.1.4)(GDH); glutamate synthase (L-glutamine: 2-exeglutarate aminotransferase (NADPH-oxidizing))(EC 2.6.1.53)(GOGAT). GS activity was high throughout the growth of the plant and GOGAT activity was always low. It is unlikely that GDH or the GS-GOGAT pathway can account for the incorporation of ammonia from dinitrogen fixation in the pea bacteroid,