Used in solid-phase peptide synthesis as a protected glutamic acid derivative, enabling sequential assembly of peptide chains with high specificity. The Fmoc group allows for mild base deprotection, while the p-nitroaniline (pNA) acts as a chromophore for real-time monitoring of coupling and deprotection reactions. Commonly applied in the synthesis of complex peptides and proteins requiring orthogonal protection strategies. Also utilized in enzyme assays where the release of p-nitroaniline indicates proteolytic activity.