Controlling the Equilibrium of Sortase-Mediated Ligations to Modify Proteins and Build Peptide Oligomers

The sortase A enzyme is a powerful protein engineering tool which allows for site-specific ligations of peptide and protein building blocks containing an LPXTG motif. However, ligation reversibility lowers the efficiency of this approach, and limits the types of structures that can be generated using sortase-based methods. Here we describe efforts to control the equilibrium of sortase-mediated ligations by sequestering certain reaction by-products or by tuning the solubility of ligation products. In this way, we are able drive ligation reactions to high levels of completion without the need for excess reagents. These strategies have proven effective in boosting the conversion of protein modification reactions, as well as promoting the formation of unique peptide oligomers that have the potential to serve as new biomaterials scaffolds