Figure 6.

Peptide backbone modifications and their Oxy enzymes' acceptance. A, chemoenzymatic synthesis of an analog 11c (Ψ[CC(=S)NH]Tpg⁴]) (42). B, incorporation of β-Dpg on teicoplanin and actinoidin sequences and its effect on the formation of the C-O-D and D-O-E rings. Building blocks indicated in the dashed squares represent the modified starting amino acids. Atoms shown in red are labeled to allow these to be traced from their origins to their positions in the final modified backbone (43).