DL-Propargyl-cysteine is a cysteine-derived amino acid derivative bearing a propargyl substituent on the thiol side chain, placing it in the class of non-proteinogenic, sulfur-containing amino acid analogues. The molecule contains both an amino group and a carboxyl group characteristic of amino acids, while the side chain features a thioether-linked propargyl functionality that provides a terminal alkyne for chemoselective labeling and conjugation chemistry. DL-Propargyl-cysteine is used as a building block in peptide and bioconjugation workflows where an alkyne handle is required for subsequent click-type coupling, and it can also serve as a substrate analogue in chemical biology and structure-activity studies focused on thiol-reactive or cysteine-mimetic behavior.
CAT No: CP08803
DL-Propargyl-cysteine is a cysteine-derived amino acid analog in which the thiol-bearing side chain is functionalized with a propargyl substituent, yielding a thioether/propargyl-containing stereochemical framework. The molecule contains the amino and carboxylate functionalities characteristic of amino acid building blocks, along with a terminal alkyne that participates in click-type and nucleophilic addition chemistry. The DL designation indicates a racemic mixture at the cysteine-derived stereocenter, which affects stereoselective peptide incorporation and downstream chiral recognition. As an amino acid intermediate, DL-Propargyl-cysteine can be used directly for derivatization or converted into protected forms for controlled peptide coupling and selective functional group transformations.
1. Peptide Synthesis
DL-Propargyl-cysteine supports peptide building block preparation where the amino acid backbone enables standard N-protection and C-terminal activation for amide bond formation. The propargyl-functionalized sulfur-containing side chain can be carried through peptide assembly under conditions compatible with terminal alkynes, allowing post-coupling functionalization such as alkyne-based conjugation or derivatization. Racemic stereochemistry can be managed at the synthesis planning stage by pairing with stereodefined coupling strategies or by using the material for libraries where stereochemical uniformity is not required. Downstream, the resulting alkyne-containing peptides can serve as intermediates for peptidomimetic construction and for generating functionalized peptide analogs for biochemical studies.
2. Chemical Biology Labeling
DL-Propargyl-cysteine is well suited to chemical biology workflows that rely on orthogonal functional handles, with the terminal alkyne enabling bioorthogonal conjugation chemistries. The amino acid core provides a handle for incorporation into peptides, linkers, or affinity reagents, while the propargyl-substituted sulfur motif can influence reactivity and conjugate stability relative to unmodified cysteine derivatives. The racemic nature can be acceptable for tagging strategies focused on chemical reactivity and subsequent detection rather than stereochemical specificity. Labeled biomolecular constructs derived from DL-Propargyl-cysteine can be used to map interaction surfaces, track biomolecule localization, or generate probes for mechanistic investigations.
3. Peptidomimetics And SAR
DL-Propargyl-cysteine can be applied in peptidomimetic design and structure-activity relationship studies where cysteine-like side chain chemistry is translated into an alkyne-bearing scaffold. The terminal alkyne enables systematic side-chain diversification through conjugation, cycloaddition, or further functional group conversion, while the amino acid backbone supports incorporation into constrained analogs that mimic peptide recognition elements. Protecting-group strategies commonly used for cysteine-derived amino acids can be adapted to manage the amine and carboxyl functions without disrupting the alkyne handle during scaffold assembly. Generated analog series can then support SAR-driven optimization of binding motifs and physicochemical properties using amino acid chemistry as the organizing framework.
4. Process Chemistry Intermediate
DL-Propargyl-cysteine serves as a chiral amino acid intermediate precursor for manufacturing routes that require an alkyne-functionalized cysteine derivative as a feedstock. The presence of both primary amine and carboxylic acid functionality supports conversion into protected amino acid derivatives, activated esters, or coupling-ready forms that integrate into downstream fine chemical synthesis. The terminal alkyne provides a chemically robust functional group for sequential transformations, enabling downstream derivatization steps in a controlled, stepwise process design. Industrially relevant use cases include preparation of alkyne-containing peptide building blocks, linker reagents, and specialty intermediates for chemical manufacturing where reproducible functional group content is required.
5. Analytical Standards
DL-Propargyl-cysteine can be employed to develop analytical standards and reference materials for monitoring amino acid derivatization, peptide coupling outcomes, and alkyne-functional group transformations. The combination of amino acid functionality and terminal alkyne provides distinct chromatographic and spectrometric signatures that facilitate method development for LC-MS or derivatization-based assays. Racemic composition can be leveraged for calibration where total concentration of the propargyl-cysteine motif is measured rather than stereospecific distribution. Reference compounds derived from DL-Propargyl-cysteine also support verification of downstream conversion steps in protected amino acid synthesis and peptide building block preparation.
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