Boc-Lys(Z)-OH is a protected amino acid used in the synthesis of peptides. It consists of a lysine residue with a tert-butyloxycarbonyl (Boc) protecting group on the α-amino group and a benzyloxycarbonyl (Z) protecting group on the ε-amino group of the lysine side chain. This protected amino acid is an important building block in the step-wise construction of more complex peptide sequences.