L-Lysine methyl ester dihydrochloride is a derivative of the essential amino acid L-lysine, primarily used as a protected building block in peptide synthesis. It is widely employed in biochemical research for the preparation of custom peptides via solid-phase or solution-phase methods, enabling studies on protein structure, function, and interactions. In pharmaceutical development, it serves as a key intermediate in the synthesis of peptide-based therapeutics, including potential antiviral and antibacterial agents. Additionally, it finds applications in biotechnology for the modification of biomolecules and enzyme studies, supporting advancements in therapeutic and diagnostic tools.