PMID:6349612
| Citation |
Boiteux, A, Markus, M, Plesser, T, Hess, B and Malcovati, M (1983) Analysis of progress curves. Interaction of pyruvate kinase from Escherichia coli with fructose 1,6-bisphosphate and calcium ions. Biochem. J. 211:631-40 |
|---|---|
| Abstract |
The influence of fructose 1,6-bisphosphate and Ca2+ on the kinetics of pyruvate kinase from Escherichia coli K12 was studied (at pH 7.0 and 25 degrees C) by using the pH-stat method for the measurement of the reaction progress as well as initial-rate analysis. The data were analysed on the basis of a concerted model with three conformational states [Markus, Plesser, Boiteux, Hess & Malcovati (1980) Biochem. J. 189, 421-433] by using a novel procedure for a computer-directed treatment of progress curves [Markus & Plesser (1976) Biochem. Soc. Trans. 4, 361-364]. By addition of fructose 1,6-bisphosphate the sigmoid kinetics with respect to phosphoenolpyruvate and Mg2+ is abolished and the activity of the enzyme is described by classical saturation kinetics. This is explained by exclusive binding of fructose 1,6-bisphosphate at an allosteric site of the conformational state that forms the active complex. We observe that Ca2+ is an activator of the enzyme at low Mg2+ and Ca2+ concentrations; otherwise it is an inhibitor. These effects can be understood by assuming that Ca2+ has the same binding properties as Mg2+, although it does not allow a catalytic turnover. |
| Links | |
| Keywords |
Calcium/metabolism; Escherichia coli/enzymology; Fructosediphosphates/metabolism; Kinetics; Magnesium/metabolism; Mathematics; Pyruvate Kinase/metabolism |
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