(2S)-Nα-benzoyllysine methyl ester hydrochloride is a protected lysine derivative, specifically the methyl ester hydrochloride salt of Nα-benzoyl-L-lysine. It features a benzoyl group protecting the alpha-amino group and a methyl ester protecting the carboxyl group, with the epsilon-amino group on the side chain remaining free. This specific protection pattern makes it a versatile building block. This compound is primarily used in peptide synthesis and biochemical research. It serves as a key intermediate for the solid-phase or solution-phase synthesis of peptides containing lysine residues, allowing for selective deprotection and further functionalization at the epsilon-amino position. It is also employed in the study of enzyme substrates and inhibitors, particularly for proteases like trypsin and plasmin, due to its structural similarity to natural lysine-containing substrates. As a chiral, protected amino acid derivative, it is a valuable synthon in organic chemistry for constructing more complex molecules beyond peptides. Its commercial availability and defined stereochemistry make it a reliable starting material for researchers in medicinal chemistry and chemical biology.