Prediction of the rate of glucose utilization from cellular levels of glucose 6-phosphate and fructose 1,6-diphosphate in Escherichia coli.

A comprehensive equation, upsilon = VM/[1 + (A0.5/Fru-P2)n] [ 1 + (Glc-6-P/I0.5)], has been proposed to represent the quantitative interrelationships between the rate of glucose utilization and the levels of glucose-6-phosphate and fructose-1,6-diphosphate in the intact Escherichia coli cell. This comprehensive equation was derived from empirical equations that describe the relationship between the rate of glucose utilization and one of these hexose phosphates in metabolic situations where the other hexoses phosphate was not altered. In the experiments described in this report, treatment of nitrogen (NH4+)-starved cultures of E. coli W4597 (K) with various concentrations of sodium azide altered the levels of both hexose phosphates as well as the rate of glucose utilization. In each case the observed rate and the rate predicted by the comprehensive equation agreed closely, substantiating the validity of this comprehensive relationship as a quantitative indicator of metabolic events in the intact cell. The mechanism of metabolic regulation that is represented by this equation is discussed in light of the cellular levels of adenosine 5'-triphosphate and phosphoenolpyruvate observed in these experiments.