Iron, an essential element for biosynthesis of aromatic compounds.

Abstract

Homogeneous preparations of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase [7-phospho-2-keto-3-deoxy-D-arabino-heptonate D-erythrose-4-phosphate lyase (pyruvate phosphorylating), EC 4.1.2.15] isolated as the enzyme.cntdot.phosphoenolpyruvate complex from Escherichia coli are shown by atomic absorption analysis to contain approximately 1 mol of Fe/mol of native enzyme. No Co was found, contrary to suggestions of earlier workers. Pure enzyme preparations show a unique absorption maximum around 350 nm with an .epsilon. value of about 3500 M-1 cm-1. The 350 nm band as well as the enzyme activity is lost when the enzyme is denatured with guanidine.cntdot.hydrochloride, or when phosphoenolpyruvate, the 1st substrate to bind to the enzyme, is totally removed from the enzyme by incubation with an excess of erythrose 4-phosphate, the 2nd substrate to bind to the enzyme. The Fe remains bound to the enzyme when phosphoenolpyruvate is removed from the enzyme.cntdot.phosphoenolpyruvate complex.