Substrate antagonism in the kinetic mechanism of E. coli phosphofructokinase-1.
In the presence of its allosteric activator GDP, the major phosphofructokinase-1 from Escherichia coli K12 follows Michaelis-Menten kinetics. The kinetic behavior observed at steady-state using different concentrations of the substrates ATP and fructose-6-phosphate and the pattern of inhibition by the substrate analogs adenylyl-(beta, gamma-methylene)-diphosphonate and D-arabinose-5-phosphate are consistent with a random sequential mechanism in rapid equilibrium, rather than with an ordered binding as was suggested earlier. However, ATP and fructose-6-phosphate do not bind independently to the same active site, since the apparent affinity for one substrate is decreased about 20-fold when the other substrate is already bound. The antagonism between ATP and fructose-6-phosphate shows that a negative interaction occurs during the reaction with E. coli phosphofructokinase-1 which must be considered in addition to its allosteric properties.
Deville-Bonne
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D
Laboratoire d'Enzymologie du CNRS, Gif-sur-Yvette, France.
Laine
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R
Garel
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JR
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D000494:Allosteric Regulation; D004926:Escherichia coli / Q000201:enzymology*; D005636:Fructosephosphates / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism; D007700:Kinetics; D010428:Pentosephosphates / Q000494:pharmacology; D010732:Phosphofructokinase-1 / Q000037:antagonists & inhibitors / Q000378:metabolism*
D005636:Fructosephosphates; D010428:Pentosephosphates; C028055:arabinose 5-phosphate; D006153:Guanosine Diphosphate; C027618:fructose-6-phosphate; D000255:Adenosine Triphosphate; D010732:Phosphofructokinase-1; C002630:alpha,beta-methyleneadenosine 5'-triphosphate