H-Lys-NH2 · 2 HCl

Lysine hydrochloride, H-Lys-NH2 · 2 HCl, is the fully protonated diamino acid salt corresponding to an L-lysine backbone with a free α-amino group and an ε-amino side chain, both present as chloride-associated species. The molecule bears two basic nitrogen functionalities that strongly influence solubility, salt formation, and acid-base behavior during peptide coupling and downstream derivatization. The stereochemical configuration at the α-carbon is fixed as L, making it a chiral amino acid starting point for stereodefined peptide building blocks and for constructing lysine-containing motifs. The salt form supports controlled handling of the polycationic functional groups, while the unprotected ε-amino functionality can be selectively protected or transformed to enable selective coupling, side-chain modification, and orthogonal deprotection strategies.

1. Protected Lysine Peptide Synthesis

Lysine hydrochloride, H-Lys-NH2 · 2 HCl, is used in peptide synthesis workflows as the L-lysine precursor that can be converted to N-protected and side-chain-protected lysine building blocks for stepwise amide bond formation. The α-amino group and ε-amino side chain provide two nucleophilic handles that, after appropriate protection, can be made compatible with standard coupling chemistries and iterative deprotection cycles. Salt-associated protonation behavior can be leveraged for controlled solubilization during protection and purification steps, while the fixed L stereochemistry supports stereodefined incorporation into peptides. Downstream, the resulting protected lysine derivatives enable construction of lysine-rich sequences, including polybasic segments used in biochemical probes and peptide-based materials.

2. Side-Chain Functionalization

Lysine hydrochloride, H-Lys-NH2 · 2 HCl, serves as a direct starting material for ε-amino side-chain functionalization in chemical biology and synthetic organic chemistry. The ε-amine can be protected to achieve chemoselectivity, then converted into acylated, alkylated, or activated intermediates that participate in subsequent coupling, crosslinking, or conjugation steps. The diamine character supports formation of stable linkages such as amide, urea, and carbamate derivatives, which can be used to tune polarity, charge density, and reactivity of lysine-containing scaffolds. Resulting functionalized lysine derivatives can be carried into peptidomimetic construction, linker synthesis, and intermediate preparation for downstream biomolecule modification.

3. Bioconjugation Linker Chemistry

Lysine hydrochloride, H-Lys-NH2 · 2 HCl, is applicable to bioconjugation chemistry where lysine ε-amines are targeted for attachment of labels, affinity handles, or imaging reagents. The free amino functionalities allow formation of conjugation-ready intermediates after conversion to protected forms or after controlled derivatization to introduce electrophilic groups for selective reaction with nucleophiles on biomolecules. The salt form can facilitate handling of the polycationic amino acid during linker synthesis, while L stereochemistry preserves structural fidelity when lysine is incorporated into peptide-based conjugates. Downstream use includes preparation of lysine-based linkers and conjugation reagents used in protein labeling, peptide-tag construction, and analytical assay development.

4. Chemical Manufacturing Intermediates

Lysine hydrochloride, H-Lys-NH2 · 2 HCl, functions as an industrial amino acid input for manufacturing intermediates that require L-lysine-derived protected derivatives and downstream functionalization. The presence of both α- and ε-amino groups enables manufacturing routes that install orthogonal protecting groups, allowing sequential processing to control which nitrogen participates in each transformation. Salt handling supports process-friendly dissolution and metering behavior, and the defined stereocenter supports consistent quality in chiral intermediate supply chains. Resulting protected lysine intermediates can be used to produce peptide building blocks, specialty fine chemicals, and amino acid-derived reagents used across peptide science and industrial chemical synthesis.

5. Analytical Standards And Calibration

Lysine hydrochloride, H-Lys-NH2 · 2 HCl, can be employed as an analytical reference material for amino acid quantification and method development in biochemical research and quality control laboratories. The compound's defined L stereochemistry and well-characterized diamine functionality make it suitable for calibration in chromatographic workflows and for validating derivatization-based detection strategies targeting primary amines. Salt-associated protonation and the two amino groups influence derivatization behavior, enabling method tuning for selective detection of lysine among other amino acids. Downstream, lysine standards support accurate measurement of lysine release, lysine-containing peptide composition, and amino acid integrity during peptide synthesis monitoring and industrial intermediate characterization.

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