H-Cys(Z)-OH is widely used in peptide synthesis as a protected form of cysteine. The Z (benzyloxycarbonyl) group protects the thiol side chain of cysteine, preventing unwanted reactions during peptide bond formation. This protection is crucial in solid-phase peptide synthesis (SPPS) to ensure the correct sequence and structure of the peptide. After synthesis, the Z group can be removed under specific conditions, typically using hydrogenolysis or acidolysis, to reveal the free thiol group. This compound is particularly valuable in the production of complex peptides and proteins where cysteine residues play a critical role in disulfide bond formation, which is essential for the stability and function of many biologically active peptides.