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NITROGEN ASSIMILATION IN MYCORRHIZAS. I. PURIFICATION AND PROPERTIES OF THE NICOTINAMIDE ADENINE DINUCLEOTIDE PHOSPHATE‐SPECIFIC GLUTAMATE DEHYDROGENASE OF THE ECTOMYCORRHIZAL FUNGUS CENOCOCCUM GRANIFORME
Author(s) -
MARTIN FRANCIS,
MSATEF YAMINA,
BOTTON BERNARD
Publication year - 1983
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1983.tb03441.x
Subject(s) - nicotinamide adenine dinucleotide phosphate , glutamate dehydrogenase , biochemistry , nicotinamide adenine dinucleotide , biology , enzyme , dehydrogenase , flavin adenine dinucleotide , nad+ kinase , cofactor , glutamate receptor , receptor , oxidase test
SUMMARY The nicotinamide adenine dinucleotide phosphate‐specific glutamate dehydrogenase (L‐gluta‐mate: NADP + oxido‐reductase, ECI .4.1 .4) of the ectomycorrhizal Ascomycete Cenococcum graniforme was purified twofold to electrophoretic homogeneity. The native enzyme was shown to have a molecular weight of 320000 and to be composed of six identical subunits with a molecular weight of 48 000. The pH optimum for the animating reaction was 7.6 NADP‐GDH showed a negative co‐operativity with respect to ammonia ( K m1 :2mM, K m2 :8 mM). The K m values for α‐ketoglutarate and NADPH were 2 mM and 0.03 mM, respectively. The physical and kinetics properties of this enzyme are similar with those reported for NADP‐GDH of other fungi. Cross‐reactivity of a rabbit monospecific antiserum raised against the NADP‐GDH from Sphaerostilbe repens , a saprophytic Ascomycete, was tested against the enzyme of C. graniforme. The immunochemical homology of both enzymes are low suggesting that a substitution occurs in amino acid residue of the protein.