Z-Trp-ONp is primarily used in peptide synthesis as a protecting group for tryptophan. The Z-group (benzyloxycarbonyl) protects the amino group of tryptophan, while the ONp (p-nitrophenyl) ester serves as an activating group for the carboxyl group, facilitating the formation of peptide bonds. This compound is particularly useful in solid-phase peptide synthesis (SPPS), where selective protection and activation are crucial for building complex peptide chains. Its application ensures efficient and controlled coupling reactions, minimizing side reactions and improving yield. Additionally, Z-Trp-ONp is employed in research settings for studying peptide structure and function, as well as in the development of peptide-based pharmaceuticals.