SNAC-tag for sequence-specific chemical protein cleavage

Site-specific protein cleavage is essential for many protein-production protocols and typically requires proteases. We report the development of a chemical protein-cleavage method that is achieved through the use of a sequence-specific nickel-assisted cleavage (SNAC)-tag. We demonstrate that the SNAC-tag can be inserted before both water-soluble and membrane proteins to achieve fusion protein cleavage under biocompatible conditions with efficiency comparable to that of enzymes, and that the method works even when enzymatic cleavages fail. SNAC-tags allow for versatile sequence-specific cleavage of soluble and membrane proteins with Ni2+ under biocompatible conditions, bypassing enzymatic cleavage and enabling cleavage in situations where commonly used enzymes fail.