Abstract: Peptide ligation strategies are important biotechnol. tools. Examples of applications using peptide ligation strategies include cyclization or pegylation of protein drugs for stability improvement, protein labeling for basic research, and preparation of protein constructs with unusual architectures such as antibody drug conjugate. Traditionally, peptide ligation is achieved by chem. methods which may need harsh conditions incompatible with biomols. More recently, enzymic ligation based on the use of peptide ligases is gaining increasing attention owing to its intrinsic specificity and mild reaction conditions. Here, we review the features and applications of one particular peptide ligase, butelase-1-a prototypical and super-efficient peptide asparaginyl ligase. Graphical Abstract: [graphic not available: see fulltext]