SnoopLigase-Mediated Peptide–Peptide Conjugation and Purification

Covalently linking together different proteins can enhance functionality for a range of applications. We have developed the SnoopLigase peptide–peptide conjugation method to easily and specifically link proteins fused to the peptides SnoopTagJr or DogTag via an isopeptide bond. SnoopLigase conjugation has been applied for enhancing enzyme resilience and for antigen oligomerization to enhance vaccine efficacy. Following conjugation, SnoopLigase and unreacted substrates can be removed by solid-phase immobilization of SnoopLigase, yielding purified protein–protein conjugates. Here, we describe procedures for designing tag-fused proteins, SnoopLigase purification, and ligation of SnoopTagJr and DogTag. We further define steps for the purification of the ligated product and quantification of ligation success.