Glutamate dehydrogenase from the extremely thermophilic archaebacterial isolate AN1.
Glutamate dehydrogenase (L-glutamate:NADP+ oxidoreductase, deaminating and transaminating, EC 1.4.1.4) was purified to homogeneity from the extremely thermophilic archaebacterial isolate AN1 (a member of the Thermococcales). The enzyme comprised a large proportion of the soluble cell protein (11%) and was purified in high yield. The molecular mass of the native enzyme was 204 kDa, while the subunit molecular mass was 47 kDa, indicating a tetrameric structure. The enzyme is specific for NADP(H) rather than NAD(H) by a factor of greater than 1000, as judged by Vmax/Km. Glutamate synthase activity was about 50% of the glutamate dehydrogenase activity. Activity was markedly enhanced by calcium, magnesium and manganese ions. The enzyme was highly thermostable with t1/2 values of 12.5 h and 47 min at 90 degrees C and 103 degrees C, respectively.
Microbial Biochemistry and Biotechnology Unit, School of Science and Technology, University of Waikato, Hamilton, New Zealand.
R C
RC
Hudson
L D
LD
Ruttersmith
R M
RM
Daniel
D001105:Archaea / Q000201:enzymology*; D004795:Enzyme Stability; D005969:Glutamate Dehydrogenase / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals; D008970:Molecular Weight; D009249:NADP / Q000737:chemistry; D013379:Substrate Specificity; D013696:Temperature
D008670:Metals; D009249:NADP; D005969:Glutamate Dehydrogenase