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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 (Km1:2mM, Km2:8 mM). The Km 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.