Fig. 4. The production of three different cyclic peptides from autocyclases.
a The design of the autocyclases used for producing cyclic SFTI, kalataB1 (kB1) and Vc1.1. The native peptide sequences are shown in black, with lines indicating the disulfide bond connectivity. The SrtA recognition sequence (LPXTG) that remains in in the peptide after the cyclisation is highlighted in red. b The identity and purity of the cyclised peptides were assessed by rpHPLC and LC/MS. Observed masses were m/z 1019.8 [M + 3H]3+ for cKB1, m/z 1139.0 [M + 2H]2+ for cVc1.1 and m/z 941.5 [M + 2H]2+ for cSFTI. Calculated masses are m/z 1019.8 [M + 3H]3+ for cKB1, m/z 1139.3 [M + 2H]2+ for cVc1.1 and m/z 942.2 [M + 2H]2+ for cSFTI.