L-Arginine hydrochloride is the hydrochloride salt form of L-arginine, a proteinogenic amino acid featuring a primary amino group and a side chain guanidinium functionality attached to the alpha carbon. The molecule bears an alpha-amino group and an alpha-carboxyl group, while protonation of the guanidinium moiety and the presence of chloride as the counterion characterize its ionic form and influence solubility behavior in aqueous media. As a free amino acid salt, it is used as a chemically defined building block for peptide and amino acid derivative synthesis and as a substrate or reference material in biochemical and analytical workflows that require arginine's guanidinium side-chain chemistry.
CAT No: CP00204
CAS No:1119-34-2
Synonyms/Alias:L-Argininehydrochloride;1119-34-2;L-Argininemonohydrochloride;(S)-2-Amino-5-guanidinopentanoicacidhydrochloride;L-ARGININEHCL;ArginineHydrochloride;Detoxargin;Argamine;Argivene;Levargin;Argininemonochloride;MinophagenA;H-Arg-OH.HCl;R-Gene;Argininemonohydrochloride;ARGININE,(L);UNII-F7LTH1E20Y;L-Arginine(hydrochloride);Arginine,hydrochloride,L-;(+)-L-Argininehydrochloride;L-Argininehydrochloride(VAN);L-(+)-Argininemonohydrochloride;NSC7914;EINECS214-275-1;L-Arginine,monohydrochloride
L-Arginine hydrochloride is the hydrochloride salt of the L-amino acid L-arginine, featuring a stereogenic center at the alpha-carbon, a primary amino group, and a guanidinium side chain that is protonated under typical peptide-coupling and aqueous conditions. The salt form improves handling by increasing water solubility while maintaining the characteristic strongly basic guanidinium functionality that strongly participates in ionic interactions and can engage in salt-bridge formation. The molecule contains both nucleophilic amine functionality and a carboxyl group that can be converted into activated derivatives for peptide bond formation, while the guanidinium group can be protected or selectively managed during synthesis to control chemoselectivity. As a chiral amino acid starting material and peptide-compatible building block precursor, L-arginine hydrochloride serves as a reliable entry point to arginine-containing peptides, guanidinium-bearing analogs, and downstream synthetic intermediates.
1. Peptide Synthesis
L-Arginine hydrochloride is used in peptide synthesis workflows where the alpha-amino and carboxyl functionalities enable standard peptide coupling after appropriate activation and protection management. The guanidinium side chain, being strongly basic and highly polar, can be protected as a guanidinium-stabilizing group during chain assembly to prevent side reactions and maintain controlled reactivity. Incorporation of the L-configuration supports stereochemically defined arginine residues in linear peptides, cyclic peptides, and peptide fragments used for biochemical assays and method development. Downstream, arginine-containing peptide products and peptide building block intermediates can be accessed through salt-to-free-base handling and orthogonal deprotection strategies compatible with common peptide synthesis chemistries.
2. Chemical Biology Probes
L-Arginine hydrochloride is applied in chemical biology and molecular recognition studies to introduce a guanidinium-bearing motif that mimics key binding interactions in protein interfaces and nucleic-acid-associated systems. The side-chain guanidinium group provides a persistent positive charge for electrostatic and hydrogen-bonding interactions, enabling targeted labeling, affinity tag construction, and probe design that relies on charge-defined recognition. Functional group interconversion at the alpha-amino or carboxyl positions can support conjugation to linkers, fluorophores, or solid supports while maintaining the arginine stereochemical identity. Resulting arginine-derived conjugates can serve as biochemical research intermediates for studying binding specificity, transport-like interactions, and protein-surface engagement.
3. Bioconjugation Chemistry
L-Arginine hydrochloride is suitable for bioconjugation strategies that require a chemically addressable amino acid scaffold with a robust, protonatable side chain. The hydrochloride salt form supports aqueous compatibility for preparing arginine-containing conjugation intermediates, while the alpha-amino and carboxyl groups can be converted into coupling-ready derivatives for attachment to biomolecules. Guanidinium functionality can influence conjugate solubility and interaction behavior, which is relevant when generating peptide conjugates, antibody fragments, or affinity ligands that must retain charge-dependent binding. Downstream formation of bioconjugates and labeled peptide constructs relies on controlled protection/deprotection of the guanidinium group to preserve chemoselective coupling and reproducible conjugation patterns.
4. Amino Acid Derivatization
L-Arginine hydrochloride supports amino acid derivatization and chiral intermediate preparation where the guanidinium side chain enables targeted functional transformations and downstream synthetic utility. The presence of both amino and carboxyl groups allows conversion into esters, activated acids, or amide-forming derivatives, while the guanidinium moiety can be protected, modified, or used as a handle for constructing guanidinium-containing analogs. Stereochemical integrity of the L-center is maintained through derivative formation, supporting consistent structure-function relationships in synthetic libraries and mechanistic studies. Resulting arginine derivatives can function as intermediates for peptidomimetic construction, guanidinium-rich scaffold generation, and process chemistry feedstocks for fine chemical synthesis.
5. Pharmaceutical Manufacturing Intermediates
L-Arginine hydrochloride is relevant to pharmaceutical manufacturing and specialty chemical production as a chiral amino acid starting material for producing arginine-containing intermediates used in API-related synthesis and formulation-adjacent workflows. The amino acid salt form enables predictable handling and feeding into downstream steps that require controlled conversion of the carboxyl and amino functionalities into activated forms for coupling or incorporation. The guanidinium side chain supports the generation of charged, polar intermediates that can be integrated into peptide-like structures, solubilizing motifs, or synthesis routes requiring defined ionic character. Industrially, the compound's well-defined stereochemistry and functional group set make it suitable for scalable preparation of protected arginine derivatives and peptide building blocks used across fine chemical manufacturing chains.
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