Boc-Cys(Bzl)-Osu is widely used in peptide synthesis as a protecting group for cysteine residues. It helps prevent unwanted side reactions during the formation of peptide bonds, ensuring the cysteine thiol group remains protected. This compound is particularly valuable in solid-phase peptide synthesis, where it allows for the controlled and sequential assembly of amino acids. Additionally, it is employed in the preparation of complex peptides and proteins, especially those requiring disulfide bond formation, as it provides stability and selectivity in the synthesis process. Its application extends to the development of pharmaceuticals, bioactive peptides, and research involving protein engineering.