Title: Characterization of an extremely thermostable glutamate dehydrogenase: a key enzyme in the primary metabolism of the hyperthermophilic archaebacterium, Pyrococcus furiosus
Abstract: Glutamate dehydrogenase (l-glutamate: NAD(P)+ oxidoreductase, deaminating, EC 1.4.1.3) from the hyperthermophilic Archeon Pyrococcus furious was purified to homogeneity by chromatography on anion-exchange, molecular-exclusion and hydrophobic-interaction media. The purified native enzyme had an Mr of 270 000 ± 15 000 and was shown to be a hexamer with identical subunits of Mr 46 000. The enzyme was exceptionally thermostable, having a half-life of 3.5 to more than 10 h at 100°C, depending on the concentration of enzyme. The Km of the enzyme for ammonia was high (9.5 mM), indicating that the enzyme is probably active in the deaminating, catabolic direction. The coenzyme utilization of the enzyme resembled the equivalent enzymes from eukaryotes rather than cubacteria, since both NADH and NADPH were recognized with high affinity .The enzyme displayed a preference for NADP+ over NAD+ that was more pronounced at low assay temperatures (50–70°C) compared with the optimal temperature for enzyme activity, 95°C.
Publication Year: 1992
Publication Date: 1992-04-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 125
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