TY - JOUR
T1 - Occurrence of two different glutamate dehydrogenase activities in the halophilic bacterium Salinibacter ruber
AU - Bonete, Maria José
AU - Pérez-Pomares, Francisco
AU - Díaz, Susana
AU - Ferrer, Juan
AU - Oren, Aharon
N1 - Funding Information:
This work was supported by funds from MCYT BIO2002-03197.
PY - 2003/9/12
Y1 - 2003/9/12
N2 - Salinibacter ruber, an extremely halophilic member of the domain Bacteria, has two different cytoplasmic glutamate dehydrogenase activities, marked as GDHI and GDHII. GDHI showed a strong dependence on high salt concentrations for stability, but not for activity, displaying maximal activity in the absence of salts. GDHII depended on high salt concentrations for both activity and stability. It catalyzed amination of 2-oxoglutarate with optimal activity in 3 M KCl at pH 8. No activating effect was found when NaCl was replaced by KCl. Only GDHII displayed activity in the deamination reaction of glutamate with an optimal pH of 9.5. Both enzymes were activated by certain amino acids (L-leucine, L-histidine, L-phenylalanine) and by nucleotides such as ADP or ATP. A low-molecular-mass cytoplasmic fraction was found to be a highly effective activator of GDHII in the presence of high NaCl concentrations.
AB - Salinibacter ruber, an extremely halophilic member of the domain Bacteria, has two different cytoplasmic glutamate dehydrogenase activities, marked as GDHI and GDHII. GDHI showed a strong dependence on high salt concentrations for stability, but not for activity, displaying maximal activity in the absence of salts. GDHII depended on high salt concentrations for both activity and stability. It catalyzed amination of 2-oxoglutarate with optimal activity in 3 M KCl at pH 8. No activating effect was found when NaCl was replaced by KCl. Only GDHII displayed activity in the deamination reaction of glutamate with an optimal pH of 9.5. Both enzymes were activated by certain amino acids (L-leucine, L-histidine, L-phenylalanine) and by nucleotides such as ADP or ATP. A low-molecular-mass cytoplasmic fraction was found to be a highly effective activator of GDHII in the presence of high NaCl concentrations.
KW - Glutamate dehydrogenase
KW - Halophilic enzyme
KW - Salinibacter ruber
UR - http://www.scopus.com/inward/record.url?scp=0642369572&partnerID=8YFLogxK
U2 - 10.1016/S0378-1097(03)00592-5
DO - 10.1016/S0378-1097(03)00592-5
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C2 - 13129625
AN - SCOPUS:0642369572
SN - 0378-1097
VL - 226
SP - 181
EP - 186
JO - FEMS Microbiology Letters
JF - FEMS Microbiology Letters
IS - 1
ER -