Fig. 2.

Structure of the substrate analogues heptaprenyl-Lipid II (1a) and heptaprenyl-Lipid IV (2a). Radiolabeled Lipid II (1b) is made chemoenzymatically using [¹⁴C]-GlcNAc as described in (20). Alternatively, an acetyl group can be incorporated on the lysines of the substrate peptide chains, with no effect on substrate utility, by treatment with ¹⁴C-acetic anhydride to give (1c) or ¹⁴C-acetic anhydride to give radiolabeled (2b) as described in (21).