Type of Ligases

Peptide ligases can be classified into two major categories: transpeptidases and acyltransferases. Transpeptidases represent the majority of characterized ligases and include enzymes such as intein, sortases, prolyl oligopeptidase (POP)-like cyclases, trypsiligases, subtilisin-like ligase (PatG), peptide asparaginyl ligases (PALs), and connectases. In contrast, acyltransferases catalyze peptide bond formation by facilitating nucleophilic amine attack on pre-activated ester or thioester intermediates. This category includes subtilisin-derived engineered variants like subtiligases, and penicillin-binding protein(PBP)-like cyclases from NRPS biosynthetic pathways.