L-Lysine monohydrochloride

L-Lysine monohydrochloride is the salt form of the essential amino acid L-lysine, featuring a primary amino group on the side chain and a second amino functionality at the alpha position, along with a carboxylic acid. The molecule exists as a chiral amino acid with defined stereochemistry at the Cα center, and the monohydrochloride salt state protonates basic nitrogens, increasing water compatibility while maintaining nucleophilic reactivity of the amine functionality upon appropriate base treatment. Lysine's aliphatic (ε-) amino group enables targeted side-chain functionalization, while the carboxyl group supports amide formation and peptide coupling chemistry after activation or protection. As a readily handled amino acid starting material and chiral building block, L-Lysine monohydrochloride serves as a practical intermediate for protected lysine derivatives, isotope-labeled analogs, and downstream synthetic routes to peptide fragments and amine-rich functional scaffolds.

1. Peptide Synthesis

L-Lysine monohydrochloride supports peptide building block preparation and peptide coupling workflows in synthetic peptide chemistry because its alpha-carboxyl group and alpha-amino functionality can be converted into protected forms compatible with standard coupling reagents. The ε-amino side chain enables incorporation of lysine-containing sequences, while selective N-protection strategies (e.g., orthogonal protection of the side-chain amine relative to the alpha-amino group) allow controlled stepwise assembly of peptide chains. The monohydrochloride salt form facilitates handling and can be transformed into protected amino acid derivatives that participate in amide bond formation under peptide synthesis conditions. Resulting lysine-bearing peptides and protected intermediates can be used for library construction, sequence optimization, and mechanistic studies in peptide science.

2. Side-Chain Functionalization

L-Lysine monohydrochloride is well suited for amino acid derivatization and side-chain functionalization in chemical biology and synthetic organic chemistry due to the presence of a primary ε-amino group that can undergo nucleophilic substitution, acylation, reductive amination, or formation of urea and amide linkages. Salt protonation modulates basicity, enabling controlled deprotonation and subsequent functional group installation using electrophiles or activated carbonyl partners. Carboxyl functionality can be protected or activated to direct chemoselective transformations, while orthogonally protected lysine derivatives can preserve one functional site for later conjugation steps. Downstream products include functionalized lysine analogs for probe development, linker synthesis, and scaffold diversification in peptidomimetic and biomolecule modification workflows.

3. Bioconjugation Chemistry

L-Lysine monohydrochloride can be applied in bioconjugation and biomolecule labeling strategies where amine-reactive chemistries target lysine residues or lysine-derived linkers for attaching tags, affinity handles, or imaging moieties. The molecule's multiple amine sites support selective conjugation when protection and deprotection logic are employed to control which nitrogen participates in coupling, enabling predictable linker architecture. The carboxyl group can be incorporated into amide or ester intermediates used as handles for further derivatization, including attachment to polymers, surfaces, or carrier molecules. Resulting lysine-based conjugation reagents and labeled intermediates are used for biochemical research intermediate preparation, analytical method development, and controlled construction of amine-functional molecular assemblies.

4. Pharmaceutical Manufacturing

L-Lysine monohydrochloride is relevant to pharmaceutical intermediate preparation and industrial chemical manufacturing because it functions as a chiral, amine-rich feedstock for producing protected lysine derivatives used in peptide and peptidomimetic synthesis. The salt form improves process handling and can be converted into N-protected amino acid intermediates that fit into industrially scalable protection, activation, and coupling sequences. The ε-amino group enables downstream formation of amide linkages, salt formation, or further functional-group transformations that can be integrated into drug substance or drug-related intermediate routes. Industrial utilization commonly includes supplying stereochemically defined lysine building blocks for fine chemical synthesis and specialty intermediate production where consistent chiral identity and functional-group reactivity are required.

5. Analytical Research Standards

L-Lysine monohydrochloride is suitable for analytical research and method development as an amino acid reference material and derivatization substrate in chromatographic and spectrometric workflows. The defined stereochemistry and well-characterized salt composition support consistent behavior during amino acid profiling, derivatization-based quantification, and calibration of analytical instruments. The presence of both alpha and side-chain amine functionalities enables formation of detectable derivatives under common derivatization chemistries, supporting targeted detection of lysine in complex matrices. Downstream use includes preparation of labeled or functionalized lysine standards and internal references for biochemical research intermediate characterization and quality control-oriented analytical studies.

1. Novel Peptide-Based PD1 Immunomodulators Demonstrate Efficacy in Infectious Disease Vaccines and Therapeutics

2. Cell-based adhesion assays for isolation of snake venom’s integrin antagonists

3. Immune responses to peptides containing homocitrulline or citrulline in the DR4-transgenic mouse model of rheumatoid arthritis

4. Multifunctional peptide-oligonucleotide conjugate promoted sensitive electrochemical biosensing of cardiac troponin I

5. Oleic acid and glucose regulate glucagon-like peptide 1 receptor expression in a rat pancreatic ductal cell line