Scintillation proximity assay for the detection of peptidoglycan synthesis

An assay for detecting peptidoglycan synthesis, which comprises the steps of:

• (1) incubating a reaction mixture comprising in aqueous medium a uridine(5′-)diphosphate (UDP)-N-acetylmuramylpentapeptide, radiolabelled UDP-N-acetyl glucosamine, divalent metal ions, undecaprenyl phosphate, peptidoglycan, translocase enzyme, transferase enzyme, transglycosylase enzyme, transpeptidase enzyme and lipid pyrophosphorylase enzyme, under conditions that allow completion of peptidoglycan synthesis;
• (2) adding a divalent metal ion chelator compound to the reaction mixture of step (1) to terminate peptidoglycan synthesis;
• (3) adding lectin-coated beads impregnated with a fluorescer to the reaction mixture of step (2), which beads bind, via the lectin coating, the radiolabelled UDP-N-acetyl glucosamine in the peptidoglycan synthesized in step (1);
• and
• (4) measuring light energy emitted by the fluorescer as a result of activation of the fluorescer by the radiation energy emitted by the radiolabelled peptidoglycan proximately bound thereto, which light energy is indicative of the presence of radiolabeled peptidoglycan synthesized in step (1).