MC-Val-Cit-PAB-Gly is a cleavable ADC linker featuring a maleimide, a valine-citrulline (Val-Cit) dipeptide, and a para-aminobenzyl (PAB) spacer ligated to a glycine residue. Maleimide is a thiol-specific covalent linker which is used to label cysteine residues in proteins while the glycine features a carboxylic acid which is free to link with amines to form amide bonds. Dipeptide cleavage by proteases triggers the PAB to efficiently release the drug payload via an elimination mechanism.
