H-Cys(Bzl)-OH

H-Cys(Bzl)-OH is a cysteine derivative featuring a free carboxylic acid and a thiol-bearing amino acid backbone protected at the side-chain sulfur as a benzyl thioether (Bzl), with the stereogenic center corresponding to the natural cysteine configuration. The benzyl group masks the highly nucleophilic and oxidation-prone thiol during handling, while the amino acid functionality remains available for standard coupling chemistry after appropriate N-protection or activation. The molecule's thioether sulfur is chemically stable under many peptide-synthesis conditions yet can be converted back to a thiol via reductive deprotection strategies, enabling downstream disulfide formation or thiol-directed conjugation. The combination of a chiral amino acid scaffold, an acid handle, and a protected side-chain sulfur makes H-Cys(Bzl)-OH a practical intermediate for peptide building block preparation and sulfur-functionalized synthetic targets.

1. Protected Cysteine Peptide Synthesis

H-Cys(Bzl)-OH is used in peptide synthesis workflows where cysteine side-chain protection is required to control chemoselectivity and minimize thiol oxidation. The carboxylic acid and amino acid backbone support activation for amide bond formation, while the benzyl thioether protects the sulfur during coupling and iterative chain assembly. The chiral center provides stereochemical fidelity consistent with native cysteine residues in peptide sequences, and the protected sulfur can be carried through synthesis before conversion to a reactive thiol. The resulting deprotected cysteine residue can then participate in disulfide bond construction or thiol-based post-coupling modifications, supporting peptide analog construction and structure-function studies.

2. Side-Chain Functionalization Chemistry

H-Cys(Bzl)-OH serves as a sulfur-functionalized amino acid intermediate for side-chain derivatization strategies that require delayed thiol exposure. The benzyl thioether acts as a stable masking group for the cysteine sulfur, allowing selective transformations of the backbone-derived functional groups while the thioether remains largely inert under many organic conditions. Thiol regeneration from the Bzl group enables subsequent formation of thiol-reactive derivatives such as disulfide-containing motifs, thioesters, or electrophile-activated conjugation handles. Downstream sulfur chemistry from the regenerated thiol supports the preparation of bioconjugation reagents, redox-responsive linkers, and cysteine-containing building blocks for synthetic organic chemistry.

3. Chemical Biology Bioconjugation

H-Cys(Bzl)-OH is applicable to chemical biology workflows that require controlled introduction of cysteine-like reactive sites into peptides, linkers, or protein-reactive constructs. The protected thiol prevents premature oxidation and side reactions during synthesis of conjugation-ready molecules, while the amino acid scaffold provides a defined stereochemical context for incorporation into biomolecule-targeting sequences. Benzyl-thioether protection supports manufacturing of conjugation intermediates that can be deprotected immediately prior to thiol-directed conjugation steps, enabling reproducible coupling to maleimide, haloacetamide, or disulfide exchange chemistries. The ability to generate a single, well-defined thiol functionality from a chiral amino acid precursor supports labeling reagent preparation and biomolecule modification studies.

4. Disulfide-Containing Peptidomimetics

H-Cys(Bzl)-OH is suitable for constructing disulfide-rich peptidomimetics and constrained peptide scaffolds where cystine formation is a key structural element. The Bzl-protected sulfur enables the cysteine residue to be incorporated into multi-step peptide assemblies without uncontrolled thiol crosslinking, while the free carboxyl group supports standard peptide coupling logic after activation. Stereochemical retention at the cysteine chiral center helps preserve the geometric and conformational preferences of cysteine-derived motifs used in receptor-binding and folding studies. Deprotection of the benzyl thioether followed by controlled oxidation can generate intramolecular or intermolecular disulfide bonds, supporting downstream formation of stabilized peptide analogs and sulfur-bridged molecular frameworks.

5. Process Chemistry Intermediate Production

H-Cys(Bzl)-OH can be employed as a process chemistry intermediate for industrial fine chemical synthesis routes that require a protected cysteine with a manageable functional-group profile. The benzyl thioether protection reduces handling sensitivity relative to free thiols, while the carboxylic acid enables conversion into activated derivatives for downstream manufacturing steps such as peptide building block preparation or further derivatization. The chiral amino acid backbone supports stereospecific incorporation into larger chiral intermediates, aligning with industrial needs for consistent stereochemical outcomes. The compound's stability under many coupling conditions makes it compatible with scalable intermediate preparation strategies for sulfur-containing specialty chemicals and peptide-manufacturing supply chains.

1. Immune responses to homocitrulline-and citrulline-containing peptides in rheumatoid arthritis

2. SERS spectrum of the peptide thymosin‐β4 obtained with Ag nanorod substrate

3. Novel Peptide-Based PD1 Immunomodulators Demonstrate Efficacy in Infectious Disease Vaccines and Therapeutics

4. Immune-awakening Saccharomyces-inspired nanocarrier for oral target delivery to lymph and tumors

5. Constitutive and inflammation-dependent antimicrobial peptides produced by epithelium are differentially processed and inactivated by the commensal Finegoldia magna and the pathogen Streptococcus pyogenes