Ac-Cys(Trt)-OH contains a cysteine amino acid backbone bearing an N-acetyl (Ac-) group and a carboxylic acid (-COOH), with the thiol side chain protected as a trityl (Trt) thioether. The molecule is a protected amino acid derivative in which the Trt group masks the cysteine sulfur functionality to reduce undesired thiol reactivity while the N-acetyl substituent modifies the amino group's chemoselectivity during peptide-related transformations. Ac-Cys(Trt)-OH is used as a building block for stepwise synthesis of peptide and thioether-containing intermediates, where controlled handling of the cysteine side chain supports preparation of defined amino acid sequences and sulfur-functionalized derivatives.
CAT No: CP26938
CAS No:27486-87-9
Synonyms/Alias:Ac-Cys(Trt)-OH;N-acetyl-S-trityl-L-cysteine;27486-87-9;CHEMBL415259;Ac-Cys(Trt)-OH;;AC1OLR7W;AC-CYS-OH;N-acetyl-S-trityl-L-cysteine;;SCHEMBL5967574;(R)-N-Acetyl-S-tritylcysteine;BDBM23808;KCVPASSMLHHOIF-QFIPXVFZSA-N;MolPort-020-003-791;ZINC4899634;EBD278919;AKOS025289472;AK170230;L-Cysteine,N-acetyl-S-(triphenylmethyl)-;S-Trityl-L-Cysteine(STLC)Analogue,37;K-6980;(2R)-2-acetamido-3-tritylsulfanylpropanoicacid;(2R)-2-acetamido-3-[(triphenylmethyl)sulfanyl]propanoicacid
Ac-Cys(Trt)-OH is an N-acetyl protected cysteine derivative bearing a trityl (Trt) protected thiol, presented as the free carboxylic acid for downstream peptide and intermediate synthesis workflows. The combination of N-acetylation and S-Trt protection provides controlled chemoselectivity by suppressing the native amine and thiol reactivity during coupling and segment assembly. This reagent is commonly selected when cysteine-containing sequences require reliable handling of the sulfur functionality while maintaining a defined amino acid building block for protected-peptide chemistry and specialized intermediate preparation.
1. Cysteine-Containing Peptide Segments
Ac-Cys(Trt)-OH is used in custom peptide synthesis to assemble cysteine-bearing segments where the side-chain thiol must remain protected to prevent disulfide scrambling and undesired thioether formation during iterative coupling. Peptide chemists rely on the S-Trt group to keep the cysteine sulfur inert through standard activation and condensation steps, enabling the incorporation of cysteine at a defined position in protected peptide intermediates. The N-acetyl group further reduces side reactions from the amino terminus during segment preparation, making this building block practical for workflows that generate peptide fragments prior to final deprotection and assembly.
2. Protected Cysteine Intermediate Development
Ac-Cys(Trt)-OH is also applied as a protected cysteine intermediate for the preparation of cysteine derivatives used in medicinal chemistry and peptide-based lead optimization. In development settings, the reagent's protected thiol and masked amine help maintain a stable, isolable intermediate that can be carried through multi-step functionalization strategies before controlled deprotection and downstream coupling. Pharmaceutical intermediate teams and peptide manufacturing laboratories commonly choose this form when they need a cysteine scaffold with minimized side reactivity, supporting reliable conversion into activated cysteine-containing building blocks or into larger protected constructs.
3. Disulfide-Controlled Peptide Assembly
Ac-Cys(Trt)-OH supports workflows where disulfide connectivity must be managed carefully, including the preparation of cystine-containing peptides and thiol-reactive peptide precursors. By keeping the cysteine thiol protected as Trt during assembly, the reagent helps prevent premature oxidation or intermolecular thiol exchange that can complicate purification and reduce yield of correctly folded disulfide patterns. After segment coupling, the protected cysteine can be carried into controlled deprotection and subsequent disulfide formation steps within the broader peptide development process, which is particularly valuable for researchers building cysteine-rich peptides for structure-function studies.
4. Chemical Biology Cysteine Precursors
Ac-Cys(Trt)-OH is used by chemical biology groups to generate cysteine-containing peptide precursors that later serve as starting materials for thiol-dependent labeling or conjugation strategies. The protected thiol allows the precursor to be synthesized and purified without uncontrolled thiol chemistry, while still providing a cysteine handle that can be unmasked under the appropriate downstream conditions to enable site-specific functionalization. This makes the reagent relevant for constructing cysteine-bearing intermediates used in probe development, affinity reagent preparation, and other peptide-based chemical biology workflows where controlled thiol availability is required.
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