Fmoc-D-Lys(Ac)-OH is the D-enantiomer of a protected lysine amino acid, primarily used in peptide synthesis as a building block. It is particularly valuable for introducing a protected D-lysine residue into peptides, ensuring selective deprotection and coupling during solid-phase peptide synthesis (SPPS). The Fmoc group protects the amino group, while the acetyl (Ac) group protects the side chain amine of lysine, allowing for controlled and sequential assembly of peptides. This compound is essential in creating peptides with specific sequences and modifications, which are widely applied in drug development, biochemical research, and the study of protein interactions. Its role in producing structurally precise peptides makes it a key component in the development of therapeutic agents and bioactive molecules.