Alloc-Val-Ala-PAB-PNP is a peptide linker with a terminal 4-Nitrophenol group and an Alloc protecting group. The peptide chain can act as a cleavable linker in drug design, such as in antibody drug conjugates (ADC). In peptide synthesis, carboxylate ester derivatives of 4-nitrophenol may serve as activated components for construction of amide moieties. The Alloc group is stable to treatment with piperidine and TFA, and can be removed in neutral conditions with catalytic amounts of Pd(PPh3)4 in the presence of PhSiH3. This allows the allyl system to work orthogonality with the most common protecting groups.
