Extremely thermostable glutamate dehydrogenase from the hyperthermophilic archaebacterium Pyrococcus furiosus.
The hyperthermophilic archaebacterium Pyrococcus furiosus contains high levels of NAD(P)-dependent glutamate dehydrogenase activity. The enzyme could be involved in the first step of nitrogen metabolism, catalyzing the conversion of 2-oxoglutarate and ammonia to glutamate. The enzyme, purified to homogeneity, is a hexamer of 290 kDa (subunit mass 48 kDa). Isoelectric-focusing analysis of the purified enzyme showed a pI of 4.5. The enzyme shows strict specificity for 2-oxoglutarate and L-glutamate but utilizes both NADH and NADPH as cofactors. The purified enzyme reveals an outstanding thermal stability (the half-life for thermal inactivation at 100 degrees C was 12 h), totally independent of enzyme concentration. P. furiosus glutamate dehydrogenase represents 20% of the total protein; this elevated concentration raises questions about the roles of this enzyme in the metabolism of P. furiosus.
Consalvi
V
V
Dipartimento di Scienze Biochimiche, Universita La Sapienza, Roma, Italy.
Chiaraluce
R
R
Politi
L
L
Vaccaro
R
R
De Rosa
M
M
Scandurra
R
R
D000596:Amino Acids / Q000032:analysis; D001105:Archaea / Q000201:enzymology*; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D005969:Glutamate Dehydrogenase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D019791:Guanidine; D006146:Guanidines / Q000494:pharmacology; D006358:Hot Temperature; D007525:Isoelectric Focusing; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D013379:Substrate Specificity; D013816:Thermodynamics
D000596:Amino Acids; D006146:Guanidines; D046911:Macromolecular Substances; D005969:Glutamate Dehydrogenase; D019791:Guanidine