Ac-Lys(Boc)-OH, or N^α-acetyl-N^ε-Boc-L-lysine, is a protected amino acid building block widely used in peptide synthesis. The Boc (tert-butyloxycarbonyl) group protects the ε-amino group of the lysine side chain, while the acetyl group caps the α-amino group, preventing unwanted reactions during peptide chain assembly. It is particularly valuable in solid-phase peptide synthesis (SPPS) and solution-phase synthesis, enabling selective deprotection and coupling steps. Additionally, it is employed in the production of modified peptides and peptidomimetics for research in drug development, biochemistry, and molecular biology. The Boc group's stability under acidic conditions makes it a reliable choice for complex peptide constructions.