The intracellular location of nitrogen metabolism enzymes in Pisum arvense L. roots

The time course changes of nitrate assimilation enzymes and their distribution has been studied in Pisum arvense roots. The results indicate that nitrate reductase (EC 1.6.6.2) and glutamine synthetase (EC 6.3.1.2) are present in the soluble fraction, and nitrite reductase (EC 1.6.6.4) and glutamate synthase (EC 2.6.1.53) are localised in the plastids. The results show that the glutamine synthetase/glutamate synthase system is the major pathway of ammonium incorporation in NO3-supplied Pisum arvense roots and glutamate dehydrogenase plays a lesser role