Figure 3.

Schematic overview of enzymatic cyclization with Sortase A and Butelase 1: (a) The cysteine transpeptidase cleaves an amide bond in the recognition sequence of the protein (15, blue) forming a thioester intermediate (17) and releasing the C‐terminal sequence (16, yellow). Subsequently, the reaction of the N‐terminus with the thioester results in the cyclized protein (18). (b) Sortase A requires L−P‐aa‐T−G as the recognition motif and an oligoglycine at the N‐terminus (15 a) to generate a cyclic protein (18 a). (c) Butelase 1 requires a3‐H−V as the recognition motif and a1‐a2 at the N‐terminus (15 b) to generate a cyclic protein (18 b).