Influence of phosphoenolpyruvate on the dynamic behavior of phosphofructokinase of Escherichia coli

The effect of phosphoenolpyruvate (PEP) and the substrate input rate (sigma(1)) on the dynamic behavior of the phosphofructokinase (EC 2.7.1.11) (PFK) of Escherichia coli is analysed. The mathematical model is based on a well defined one and all kinetic parameters used in this analysis correspond specifically to the PFK of E. coli. Results agree with previous reports only when the concentration of PEP is very low (<10 mu M) but change at higher concentrations. The analysis of the local stability of PFK reveals the existence of nodes, spirals of limit cycles whose dynamic maps depended on the concentration of PEP and the substrate input rate. Phosphofructokinase shows higher sensitivity at concentrations of PEP close to those expected in E. coli (0.1-0.5 mM). The effect of PEP on the stability of PFK is complex and depends on the range of PEP concentration and sigma(1). For a given value of PEP (e.g. 1 mM), PFK can change or even reverse the stability pattern when sigma(1) changes within a particular range of values of this variable. (C) 1996 Academic Press Limited