H-Lys(Me)-OH · HCl

H-Lys(Me)-OH · HCl is a hydrochloride salt of an L-lysine derivative bearing a methyl-substituted side chain, presenting the canonical α-amino acid framework with an α-carboxylic acid and a protected/modified ε-amino functionality in the form of a methylated lysine analog. The salt form (HCl) protonates basic nitrogen sites, increasing aqueous compatibility and stabilizing the cationic form during handling and coupling setup. The stereogenic center at the α-position is retained in the L-configuration, which is critical for stereochemically controlled peptide bond formation and for maintaining recognition patterns in amino acid-dependent biochemical assays. The presence of a basic, nucleophilic side-chain nitrogen and a free carboxyl group enables standard amino acid derivatization and downstream transformation into peptide building blocks or functionalized intermediates.

1. Protected Amino Acid Chemistry

H-Lys(Me)-OH · HCl supports protected amino acid synthesis workflows where the protonated ε-amino and α-carboxyl groups can be selectively addressed through orthogonal protection strategies. The L-configuration and the basic side-chain nitrogen enable formation of N-protected derivatives for controlled peptide coupling while retaining the carboxyl functionality for activation. Salt stabilization by HCl can facilitate reproducible conversion to activated esters or acid derivatives under process-relevant conditions, and subsequent deprotection can regenerate the free amine for further functionalization. Lysine-derived intermediates incorporating methyl substitution can also serve as stereochemically defined building blocks for preparing C-terminal or side-chain modified peptide analogs.

2. Peptide Synthesis

H-Lys(Me)-OH · HCl is suitable for peptide construction where lysine-like side-chain chemistry is required, including incorporation into linear peptides and protected peptide fragments. The α-carboxylic acid and α-amino group participate in peptide coupling chemistry, while the ε-amino functionality can be managed via protection to control chemoselectivity during sequential assembly. The methyl substitution on the lysine side chain can influence steric environment and local conformational preferences, which is relevant when generating peptide libraries for structure-activity relationship studies or for tuning solubility and aggregation behavior. The hydrochloride salt form can be advantageous for consistent handling during automated or semi-automated peptide building block preparation, feeding downstream synthesis of protected amino acid residues and peptide intermediates.

3. Side-Chain Functionalization

H-Lys(Me)-OH · HCl can be applied to side-chain functionalization routes that transform the lysine-derived nitrogen into conjugatable handles or reactive intermediates. The basic ε-amino site, stabilized as a hydrochloride salt, can be converted into N-alkylated, N-acylated, or N-activated derivatives that participate in subsequent coupling to electrophiles or activated carbonyls. Methyl substitution can modulate nucleophilicity and steric accessibility, enabling controlled derivatization patterns for generating amino acid derivatives used in chemical biology probes or peptidomimetic scaffolds. Downstream utility includes preparing functionalized amino acid intermediates for conjugation chemistry, crosslinker synthesis, and scaffold diversification where side-chain reactivity must be tuned without disrupting the α-amino acid backbone.

4. Chemical Biology Probes

H-Lys(Me)-OH · HCl serves as a chiral amino acid intermediate for chemical biology research requiring lysine-like residues with altered side-chain sterics. The L-configuration supports stereochemically defined incorporation into peptide probes, while the carboxyl group and basic side-chain nitrogen enable conversion into labeled or reactive analogs through standard derivatization and activation sequences. Protonation by HCl can improve handling and reproducibility when preparing probe precursors for subsequent conjugation to tags such as fluorophores, affinity handles, or reactive groups used in biomolecular interaction studies. The methyl-substituted lysine motif can be leveraged to probe how side-chain substitution affects molecular recognition, binding site accommodation, and local electrostatics in peptide-based assays.

5. Pharmaceutical Intermediate Preparation

H-Lys(Me)-OH · HCl is applicable to pharmaceutical intermediate preparation where amino acid derivatives are used as chiral building blocks for active ingredient synthesis and process chemistry. The α-carboxylic acid and amino functionality enable conversion into protected intermediates suitable for stepwise synthesis of peptide-like fragments, amide-forming units, or amino acid-derived stereocenters. The hydrochloride salt form supports consistent material transfer and can facilitate formation of downstream activated species used in fine chemical manufacturing routes. Methyl-substituted lysine analogs can also contribute to designing constrained or sterically tuned intermediates for peptidomimetic construction, supporting scalable synthesis planning for amino acid-based scaffolds and their derivatives.

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