Glutamate dehydrogenase from the thermoacidophilic archaebacterium Sulfolobus solfataricus.
An NAD(P)-dependent glutamate dehydrogenase was purified to homogeneity from the thermoacidophilic archaebacterium Sulfolobus solfataricus. The enzyme is a hexamer (subunit mass 45 kDa) which dissociates into lower states of association when submitted to gel filtration. Isoelectric focusing analysis of the purified enzyme showed a pI of 5.7 and occasionally revealed microheterogeneity. The enzyme is strictly specific for the natural substrates 2-oxoglutarate and L-glutamate, but is active with both NADH and NADPH. S. solfataricus glutamate dehydrogenase revealed a high degree of thermal stability (at 80 C the half-life was 15 h) which was strictly dependent on the protein concentration. Very high levels of glutamate dehydrogenase were found in this archaebacterium which suggests that the conversion of 2-oxoglutarate and ammonia to glutamate is of central importance to the nitrogen metabolism in this bacterium.
Consalvi
V
V
Dipartimento di Scienze Biochimiche, Università La Sapienza, Roma, Italy.
Chiaraluce
R
R
Politi
L
L
Gambacorta
A
A
De Rosa
M
M
Scandurra
R
R
D001105:Archaea / Q000201:enzymology* / Q000254:growth & development; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D005969:Glutamate Dehydrogenase / Q000302:isolation & purification* / Q000378:metabolism; D007526:Isoelectric Point; D007700:Kinetics; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D013379:Substrate Specificity
D009243:NAD; D009249:NADP; D005969:Glutamate Dehydrogenase