Used extensively in peptide synthesis, particularly in solid-phase peptide synthesis (SPPS) methods. It serves as a protected form of L-citrulline, where the Fmoc group acts as a temporary protecting group for the amino group during the synthesis process. This allows for the sequential addition of amino acids to build peptides with high precision. It is especially valuable in the production of peptides for research, pharmaceuticals, and biotechnology applications, where citrulline-containing peptides are of interest due to their role in immune regulation and other biological processes. Additionally, it is utilized in the study of post-translational modifications, such as citrullination, which is relevant in autoimmune diseases like rheumatoid arthritis.