Isolation and characterization of the thermoresistant gluconokinase from Escherichia coli.
It is known that two gluconokinases are inducibly expressed during the utilization of gluconate by E. coli. One is thermoresistant (activity stable for 3 h at 30 degrees C) and the other thermosensitive (losses 75% or more of its activity under the above conditions). The thermoresistant gluconokinase (EC 2.7.1.12) was isolated, purified and characterized for the first time from the E. coli mutant Ca26, a K12 derivative which lacks the thermosensitive activity. The enzyme was purified 43 fold with a recovery of 11%. The M(r) of the enzyme was 100 kDa with three equal subunits of approximately 29.5 kDa. The enzyme exhibited Michaelis-Menten kinetics and the Km values for gluconate and ATP were 0.02 mM and 0.045 mM respectively.
Centro de Biología Celular, Escuela de Biologia, Facultad de Ciencias, Universidad Central de Venezuela, Caracas.
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D004926:Escherichia coli / Q000201:enzymology*; D007700:Kinetics; D008970:Molecular Weight; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D013696:Temperature
D017853:Phosphotransferases (Alcohol Group Acceptor); C020578:gluconokinase