Alloc-Val-Ala-PAB-PNP is an ADC linker featuring an alloc-protected amine, a Val-Ala dipeptide, a PAB group, and a PNP carbonate. The PNP carbonate is highly activated towards attack from amines to form carbamate structures with a given payload, while the alloc protecting group can be removed by palladium catalysts to free the N-terminal amine to react with a wide variety of structures such as carboxylic acids. The Val-Ala dipeptide is cleaved by proteases to release a given drug payload via an elimination mechanism within the PAB group.
