L-Propargyl-cysteine is a cysteine-derived amino acid bearing a thiol-containing side chain and an additional propargyl substituent on the sulfur, classifying it as a sulfur-functionalized, non-proteinogenic cysteine analogue suitable for peptide and bioconjugation chemistry. The molecule contains an amino group and a carboxyl group on the α-carbon, with stereochemistry indicated as L for the amino acid backbone, and it features a propargyl (alkyne) functional handle alongside the thioether-linked sulfur functionality. In synthesis and chemical biology workflows, the alkyne enables orthogonal coupling and labeling strategies, while the cysteine-like scaffold supports incorporation into peptide-related intermediates and the preparation of structured amino acid derivatives for structure-activity studies and analytical method development.
CAT No: CP08802
L-Propargyl-cysteine contains a L-cysteine-derived backbone bearing a side-chain thiol and a propargyl substituent, providing a chiral, sulfur-containing amino acid with an alkyne handle for orthogonal functionalization. The molecule features a free or derivatizable amino group and a carboxylic acid (depending on salt/form), while the propargyl group introduces a terminal alkyne that can participate in copper-catalyzed azide-alkyne cycloaddition, thiol-specific conjugation, and subsequent click-compatible derivatization. The thiol functionality can be protected and later revealed to enable controlled peptide coupling or selective chemoselective ligation, while the stereogenic center supports stereodefined incorporation into peptide and peptidomimetic frameworks. As a chiral amino acid intermediate, L-Propargyl-cysteine can be used to construct sulfur- and alkyne-functionalized derivatives that serve as downstream building blocks for biochemical probes, synthetic scaffolds, and industrial intermediate preparation.
1. Peptide Synthesis
L-Propargyl-cysteine supports peptide building block preparation for N- and C-terminally defined syntheses because its amino acid backbone participates in standard coupling chemistry while the side-chain thiol can be protected to prevent disulfide formation during chain assembly. The propargyl substituent introduces an alkyne functionality that remains chemically addressable under many peptide synthesis conditions, enabling post-coupling click modification of the resulting peptide or thioether-stabilized analogs. Thiol protection and deprotection strategies can be selected to match the orthogonality requirements of on-resin or solution-phase peptide assembly, allowing controlled generation of cysteine-derived motifs. The stereochemistry of the L-configuration enables stereodefined incorporation into peptide sequences and can be leveraged for peptide analog construction and structure-activity relationship studies.
2. Chemical Biology Probes
L-Propargyl-cysteine is suitable for chemical biology workflows that require cysteine-reactive handles combined with a bioorthogonal alkyne for downstream labeling. The terminal alkyne enables azide-alkyne cycloaddition to install fluorophores, affinity tags, or reporter groups after peptide or protein fragment incorporation, while the thiol can be used to generate thioether conjugates or to form reversible capture intermediates depending on the protection state. The amino acid scaffold provides a stereochemically defined incorporation point into peptides and small molecules used for target engagement studies, pathway mapping, or labeling strategies. Downstream derivatives can be prepared as click-ready intermediates for probe generation and as modular reagents for biochemical research intermediate preparation.
3. Bioconjugation Chemistry
L-Propargyl-cysteine can be employed in bioconjugation chemistry where sulfur functionality and an alkyne handle enable sequential, chemoselective attachment strategies to biomolecules. The side-chain thiol supports controlled formation of thioether linkages or conjugation intermediates after appropriate protection/deprotection, while the propargyl group provides a stable alkyne for click-compatible conjugation to azide-bearing partners. The presence of a chiral amino acid backbone facilitates incorporation into peptide linkers, affinity peptides, or protein-binding scaffolds used for conjugate construction. The resulting functionalized conjugates can serve as intermediates for biomolecule labeling and as platform molecules for building larger bioconjugate libraries in applied research settings.
4. Peptidomimetic Construction
L-Propargyl-cysteine enables peptidomimetic construction by providing a cysteine-derived stereocenter and a side-chain thiol that can be converted into thioether, sulfenamide, or other sulfur-containing motifs while retaining the alkyne for further diversification. The propargyl group can be carried through scaffold assembly and later transformed via click chemistry or alkyne functional group interconversions to introduce rings, linkers, or steric/electronic modifications. Thiol protection strategies allow compatibility with peptide coupling conditions, enabling incorporation into constrained analogs where cysteine-like reactivity is controlled. The compound thus functions as a chiral amino acid intermediate for generating stereodefined peptidomimetics used in molecular design and SAR-aligned scaffold elaboration.
5. Process Chemistry Intermediate
L-Propargyl-cysteine is applicable as a process chemistry intermediate for fine chemical synthesis routes that require a chiral sulfur-containing amino acid with an orthogonal alkyne handle. The amino acid functional groups support conversion into protected amino acid derivatives, enabling downstream manufacturing of N-protected building blocks for peptide coupling and of thiol-protected intermediates for controlled reactivity management. The terminal alkyne can be preserved through protected amino acid synthesis steps and then used as a handle for late-stage derivatization, aligning with industrial strategies that minimize protecting-group cycling. The compound's defined stereochemistry and functional group array support scalable intermediate preparation for specialty chemical production, including click-reactive linker manufacture and sulfur-functional scaffold generation.
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