title: Purification and properties of an extreme thermostable glutamate dehydrogenase from the archaebacterium Sulfolobus solfataricus.
abstract: Glutamate dehydrogenase (L-glutamate:NAD(P)+ oxidoreductase, deaminating, EC 1.4.1.3.) of the extreme thermophilic archaebacterium Sulfolobus solfataricus was purified to homogeneity by (NH4)2SO4 fractionation, anion-exchange chromatography and affinity chromatography on 5'-AMP-Sepharose. The purified native enzyme had a Mr of about 270,000 and was shown to be a hexamer of subunit Mr of 44,000. It was active from 30 to 95 degrees C, with a maximum activity at 85 degrees C. No significant loss of enzyme activity could be detected, either after incubation of the purified enzyme at 90 degrees C for 60 min, or in the presence of 4 M urea or 0.1% SDS. The enzyme was catalytically active with both NADH and NADPH as coenzyme and was specific for 2-oxoglutarate and L-glutamate as substrates. With respect to coenzyme utilization the Sulfolobus solfataricus glutamate dehydrogenase resembled more closely the equivalent enzymes from eukaryotic organisms than those from eubacteria.
authors.affiliation: Institut für Mikrobiologie, Medizinische Fakultät der Universität Innsbruck, Austria.
authors.forename: M F
authors.initials: MF
authors.lastname: Schinkinger
authors.forename: B
authors.initials: B
authors.lastname: Redl
authors.forename: G
authors.initials: G
authors.lastname: Stöffler
mesh_terms: D000596:Amino Acids / Q000032:analysis; D001105:Archaea / Q000201:enzymology*; D005969:Glutamate Dehydrogenase / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008970:Molecular Weight; D011489:Protein Denaturation
chemical_list: D000596:Amino Acids; D005969:Glutamate Dehydrogenase