Fmoc-Lys-OH·HCl is widely used in peptide synthesis as a building block. It is particularly valuable for introducing lysine residues into peptides while protecting the amino group with the Fmoc (9-fluorenylmethoxycarbonyl) group. This chemical is essential in solid-phase peptide synthesis (SPPS), where it ensures controlled and efficient coupling reactions. It is also employed in the development of peptide-based drugs, biomaterials, and research tools. Additionally, its compatibility with automated synthesizers makes it a preferred choice for high-throughput peptide production.