ANTICAPSIN, AN ACTIVE-SITE DIRECTED IRREVERSIBLE INHIBITOR OF GLUCOSAMINE-6-PHOSPHATE SYNTHETASE FROM ESCHERICHIA COLI

Abstract

Glucosamine-6-phosphate synthetase from Escherichia coli K-12 is progressively inactivated by L-β-(2, 3-epoxycyclohexyl-4-on)alanine (anticapsin). With increasing concentrations of anticapsin the reaction exhibits rate saturation: the minimum inactivation half-time is 1.15 minutes, with a K_inact of 2.5μM. Glutamine and competitive inhibitors protect against inactivation. Fructose-6-phosphate promotes the inactivation rate. It is concluded that anticapsin is an active-site directed glutamine analog in the reaction catalyzed by glucosamine-6-phosphate synthetase.