Enzymes of nitrogen metabolism in legume nodules. Purification and properties of NADH-dependent glutamate synthase from lupin nodules.
An NADH-dependent glutamate synthase has been purified 500-fold from the plant cytoplasm fraction of Lupinus angustifolius nodules. It consists of a single polypeptide chain, Mr 235000. The optimum  pH is 8.5, at which Km values for 2-oxoglutarate, glutamine and NADH are 39 micrometer, 400 micrometer and 1.3 micrometer respectively. The catalytic centre activity is of the order of 70 s-1 and is independent of pH between 6.5 and 9.5. Glutamate synthase is inhibited by glutamic acid, oxaloacetic acid, aspartic acid and asparagine, all competitive with 2-oxoglutarate; and by NAD+, which is competitive with NADH. There is evidence of two flavine prosthetic groups per enzyme molecule.
D005970:Glutamate Synthase / Q000037:antagonists & inhibitors / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D009243:NAD / Q000378:metabolism; D010944:Plants; D011489:Protein Denaturation; D013057:Spectrum Analysis; D013379:Substrate Specificity; D000637:Transaminases / Q000302:isolation & purification*
D009243:NAD; D005970:Glutamate Synthase; D000637:Transaminases