Z-Gln-ONp is widely used in peptide synthesis as a protecting group for glutamine. It helps in preventing unwanted side reactions during the formation of peptide bonds. The compound is particularly valuable in solid-phase peptide synthesis (SPPS), where it allows for the selective deprotection and activation of specific amino acids. Its application ensures higher yields and purity of the synthesized peptides, making it essential in the production of complex peptides for research and pharmaceutical development. Additionally, it is utilized in enzymatic studies to investigate the activity and specificity of proteases and other enzymes involved in peptide processing.