Substrate specificity of MupP. Twenty-five millimolar GlcNAc 1P, GlcNAc 6P, MurNAc 1P, MurNAc 6P, GlcN 6P, Glc 1P, or Glc 6P was incubated with 1.93 mM (50 mg/liter) recombinant MupP enzyme. Samples were loaded onto TLC plates at time zero and after 3 h of incubation at 37°C.