Self‐Stabilization of the Energy Charge in a Reconstituted Enzyme System Containing Phosphofructokinase

Abstract

The self-stabilization of the energy charge and of ATP was investigated in an open reconstituted enzyme system containing phosphofructokinase (EC 2.7.1.11) pyruvate kinase (EC 2.7.1.40), adenylate kinase (EC 2.7.4.3) and G-6-P isomerase (EC 5.3.1.9). The experiments were performed in a stirred flow-through reactor containing gel-entrapped enzymes. The dynamics of the system were analyzed theoretically by a model based on the kinetic properties of the individual enzymes. The energy charge was identified as one of the essential variables of the system. According to the theoretical prediction, homoeostasis of the energy charge was observed experimentally when either the maximal activity of phosphofructokinase, the energy charge of the influx solution or the flow rate through the reaction chamber was varied. The efficiency of stabilization of the energy charge is apparently related to the occurrence of alternative stationary states.