A continuous, anaerobic spectrophotometric assay for chorismate synthase activity that utilizes photoreduced flavin mononucleotide.

A sensitive, continuous, spectrophotometric assay for chorismate synthase has been developed utilizing photoreduced flavin mononucleotide (FMNH2) as a cofactor under anaerobic conditions. The assay monitors directly the formation of chorismate from 5-enolpyruvylshikimate-3-phosphate (EPSP) at 275 nm with a precision of +/- 2 microM product. The assay conditions have been optimized with respect to FMNH2 (cofactor), EPSP (substrate) and enzyme concentrations, buffer type, and pH. The potential of the assay for detailed steady-state kinetic studies to elucidate the mechanism of action of this commercially important enzyme is also demonstrated.