Open AccessEnzymes of Nitrogen Metabolism in Legume Nodules
Author(s) -
BOLAND Michael J.,
BENNY A. Graeme
Publication year - 1977
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1977.tb11816.x
Subject(s) - legume , enzyme , nitrogen cycle , biochemistry , metabolism , chemistry , nitrogen , biology , botany , organic chemistry
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, M r 235000. The optimum pH is 8.5, at which K m values for 2‐oxoglutarate, glutamine and NADH are 39 μM, 400 μM and 1.3 μM 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.