H-D-Cys(Mbzl)-OH is a deuterated, protected cysteine derivative featuring a thioether side chain bearing a benzyl (Mbzl) substituent, with the amino acid backbone containing both an amino group and a carboxylic acid. The "H-D" notation indicates incorporation of deuterium at a specific hydrogen position on the cysteine framework, while the Mbzl group masks the native cysteine thiol functionality by converting it into a benzyl-protected thioether, and the molecule is presented as the free carboxylic acid. This compound is used as a labeled amino acid building block for peptide synthesis and for analytical or chemical biology studies where cysteine side-chain chemistry and isotopic labeling are required to track incorporation, perform structure-activity comparisons, or support detection in labeling-based workflows.
CAT No: CP26283
CAS No:127348-02-1
Synonyms/Alias:S-4-Methylbenzyl-D-cysteine;127348-02-1;AC1OJ5U1;SCHEMBL919742;S-(4-methylbenzyl)-D-cysteine;CTK8E6393;QOAPFSZIUBUTNW-SNVBAGLBSA-N;ZINC4668209;7682AH;RT-015606;K-3970;(2S)-2-amino-3-[(4-methylphenyl)methylsulfanyl]propanoicacid
H-D-Cys(Mbzl)-OH is a deuterated, N-protected cysteine derivative in which the amino acid backbone is present as an α-amino acid bearing a thiol-containing side chain masked as an S-benzyl thioether (Mbzl) and an acid terminus suitable for peptide coupling. The stereogenic center corresponds to D-cysteine configuration, enabling stereochemically defined incorporation into peptide analogs and mechanistic studies where enantiomer identity matters. The thioether-protected sulfur is stable under many coupling conditions yet can be converted to reactive thiol functionality via established deprotection or side-chain transformation strategies, supporting redox-sensitive chemistry typical of cysteine residues. The deuterium label provides an isotopically distinct handle for mass spectrometric tracking and kinetic or metabolic tracing, while the carboxylic acid enables downstream activation to amide and thioether-linked derivatives in synthetic organic chemistry.
1. Isotope-Labeled Peptide Studies
H-D-Cys(Mbzl)-OH is used in chemical biology and analytical research for constructing deuterium-labeled cysteine-containing peptides and peptide fragments. The D-stereochemistry and the S-benzyl thioether protect the cysteine side chain during peptide coupling, while the free carboxylic acid supports conversion to activated species for amide bond formation. Deuterium incorporation can be monitored by LC-MS or MS/MS to distinguish labeled fragments, enabling studies of peptide stability, proteolysis patterns, and cysteine-containing motif behavior. Labeled products derived from this amino acid can serve as reference standards or mechanistic probes in peptide chemistry and biomolecular interaction assays.
2. Protected Amino Acid Synthesis
H-D-Cys(Mbzl)-OH is suitable for protected amino acid chemistry and synthetic intermediate preparation, where cysteine side-chain protection and stereochemical control are required. The Mbzl thioether masks the thiol functionality, reducing undesired oxidation or side reactions during coupling and protecting-group manipulations. The deuterated α-position and D-configuration allow preparation of stereodefined chiral building blocks for unnatural amino acid incorporation workflows and for mapping stereochemical outcomes in derivatization sequences. The carboxylic acid functionality can be employed to generate peptide-ready intermediates for fine chemical synthesis and process-oriented assembly of cysteine-containing scaffolds.
3. Peptide Coupling Chemistry
H-D-Cys(Mbzl)-OH functions as a cysteine-based peptide building block in peptide synthesis where controlled thioether-to-thiol conversion or cysteine mimic chemistry is required. The amino acid framework supports standard peptide coupling logic through carboxyl activation, while the S-benzyl thioether provides a stable handle that can be retained through multiple steps before selective side-chain transformation. D-cysteine stereochemistry can be incorporated to probe stereochemical effects on folding, aggregation propensity, or binding-site recognition in peptide analog libraries. Downstream derivatives formed from this building block can include thioether-stabilized peptidomimetics and cysteine-containing peptide segments used in SAR studies and molecular design campaigns.
4. Bioconjugation Linker Development
H-D-Cys(Mbzl)-OH can be applied in biomolecule modification and bioconjugation chemistry to generate cysteine-reactive conjugation motifs after controlled side-chain unmasking. The protected sulfur reduces premature thiol reactivity during synthesis of conjugate precursors, while the D-configuration can be leveraged to tune stereochemical recognition in binding assays or to create stereochemically defined conjugates. The carboxylic acid group enables attachment to linkers, solid supports, or carrier proteins via amide formation, producing conjugate-ready intermediates for labeling workflows. Resulting conjugates can be used to investigate protein surface chemistry, receptor-ligand interactions, or peptide-mediated targeting using cysteine-based coupling strategies.
5. Peptidomimetics And SAR Studies
H-D-Cys(Mbzl)-OH is appropriate for peptidomimetic construction and structure-activity relationship studies where cysteine residues are replaced or stabilized as thioether-protected analogs. The Mbzl-protected side chain provides a chemically defined sulfur functionality that can participate in later oxidation-state adjustments or serve as a cysteine mimic depending on the synthetic route. D-stereochemistry supports creation of stereochemically constrained analogs that help disentangle stereochemical contributions to binding and conformational preferences. Downstream analogs derived from this amino acid-based intermediate can be incorporated into fragment libraries and SAR panels to support molecular design decisions in applied peptide science and synthetic organic methodology.
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