(Ac-Cys-OH)2 is a cysteine-containing amino acid derivative consisting of two cysteine residues in an N-acetylated form, with each residue bearing a free carboxylic acid group (-COOH) and a thiol-bearing side chain (-CH2-SH) characteristic of cysteine. The molecule therefore presents two amino-acid backbones with N-acetyl protection on the amino termini, while retaining reactive sulfhydryl functionality that can participate in thiol-disulfide chemistry or be used for selective functionalization under appropriate conditions. In synthetic and analytical workflows, (Ac-Cys-OH)2 is used as a defined cysteine building block or intermediate for preparing cysteine-containing peptides, for studying thiol reactivity and conjugation chemistry, and for generating more complex amino acid derivatives with controlled N-terminal acetylation.
CAT No: CP27203
CAS No:5545-17-5
Synonyms/Alias:Boc-3-(1-naphthyl)-L-alanine;55447-00-2;Boc-L-1-naphthylalanine;Boc-1-Nal-OH;(S)-N-Boc-L-(1-naphthyl)alanine;Boc-L-3-(1-Naphthyl)-alanine;(2S)-2-[(tert-butoxy)carbonylamino]-3-naphthylpropanoicacid;ST50307422;3-(NAPHTHALEN-1-YL)-N-BOC-L-ALANINE;(2S)-2-[(tert-butoxycarbonyl)amino]-3-naphthalen-1-ylpropanoicacid;(2S)-2-[(tert-butoxycarbonyl)amino]-3-(naphthalen-1-yl)propanoicacid;PubChem11940;Boc-D-1-Nal-OH;AC1ODW8G;BOC-L-1NAL-OH;BOC-NA(1)-OH;KSC491O8R;15347_ALDRICH;BOC-ALA(1-NAPH)-OH;SCHEMBL613640;15347_FLUKA;CTK3J1788;KHHIGWRTNILXLL-HNNXBMFYSA-N;MolPort-001-758-473;BOC-L-ALA(1-NAPHTHYL)-OH
Ac-Cys-OH is a cysteine derivative in which the α-amino group is acetylated, providing a defined, non-proteinogenic building block for cysteine-containing peptide and thioether-rich sequences. The presence of a free carboxylic acid and a thiol-bearing cysteine side chain makes it useful for controlled incorporation into peptide frameworks and for downstream thiol chemistry under conditions compatible with cysteine residues. As a dimeric supply format, (Ac-Cys-OH)2 is commonly handled as a cysteine source for preparative peptide segments and cysteine-functional materials where thiol availability and defined acetylation are important.
1. Cysteine Segment Building
Ac-Cys-OH)2 is used as a cysteine-containing segment source for constructing short peptides and peptide-like linkers where thiol functionality must be retained for subsequent coupling or modification steps. Researchers performing custom peptide synthesis and peptide library assembly rely on the acetylated amino terminus to reduce variability in terminal reactivity and to support consistent downstream condensation strategies when building defined cysteine patterns. In peptide workflows, the free thiol allows sequential functionalization after segment assembly, enabling access to cysteine-specific conjugates without introducing additional thiol-bearing amino acid variability.
2. Thiol-Functional Conjugation
Ac-Cys-OH)2 is frequently selected for workflows that require controlled thiol availability for bioconjugation and chemical biology labeling. The cysteine thiol enables attachment to maleimide-activated surfaces, thiol-reactive electrophiles, and other sulfhydryl-targeted coupling chemistries used to generate defined thioether-linked conjugates. Bioconjugation teams and materials scientists use this format to introduce cysteine-derived handles into peptides, linkers, and polymer conjugates while maintaining an acetylated amino group that can help standardize reactivity during multi-step labeling sequences.
3. Cysteine-Rich Linker Synthesis
Ac-Cys-OH)2 supports the preparation of cysteine-rich linkers and intermediate fragments used in protein engineering and chemical modification studies. Protein chemists often incorporate cysteine units to create defined attachment points for subsequent conjugation, crosslinking, or affinity-tagging strategies, with the acetylated amino functionality helping maintain a predictable intermediate profile during linker assembly. This reagent format is also used in the development of cysteine-functional biomaterials and peptide-based scaffolds where thiol-directed attachment chemistry is a key design element.
4. Analytical Reference Preparation
Ac-Cys-OH)2 is used in analytical chemistry and method development as a defined cysteine-containing standard for monitoring derivatization and thiol-reactive labeling performance. Analytical method developers use cysteine derivatives to evaluate reaction completeness, quantify labeling efficiency, and verify LC-MS or related workflows that depend on thiol-specific derivatization steps. Because the reagent provides a defined acetylated cysteine motif with an accessible sulfhydryl group, it is a practical reference material for optimizing sample preparation and ensuring reproducible signal generation in thiol-handling assays.
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