Proteins that are site-specifically modified with peptides and chemicals can be used as novel therapeutics, imaging tools, diagnostic reagents and materials. However, few enzyme-catalyzed methods are currently available to selectively conjugate peptides to internal sites within proteins. To overcome this problem, the Clubb, Loo and Ton-That laboratories have developed a new enzyme reagent that labels proteins with peptides via a specific lysine-isopeptide bond at high yield. The new tool may be useful in creating antibody drug conjugates.

McConnell SA, Amer BR, Muroski J, Fu J, Loo RO, Loo JA, Osipiuk J, Ton-That J and Clubb RT. Protein labeling via a specific lysine-isopeptide bond using the pilin polymerizing sortase from Corynebacterium diphtheria. Journal of the American Chemical Society 140 2018; 8420-8423.