Fmoc-Cys(Acm)-OH

Fmoc-Cys(Acm)-OH is an orthogonally protected cysteine building block specifically designed for the synthesis of complex, disulfide-rich peptides by Fmoc solid-phase peptide synthesis. The Acm protecting group on the cysteine thiol is stable throughout chain assembly and final TFA cleavage, enabling the sequential or simultaneous formation of multiple disulfide bonds in the final peptide. This orthogonal protection strategy allows researchers to selectively deprotect cysteine residues using Hg(II), Ag(I), Tl(III), or I₂ treatment, generating either free cysteinyl peptides (by reductive cleavage) or cystinyl peptides (by oxidative cyclization). Fmoc-Cys(Acm)-OH is essential for the synthesis of complex peptides and proteins where maintaining thiol integrity is critical, making it highly valued in research focused on disulfide-bonded structures, redox studies, and protein folding analysis. In quality control contexts, this compound serves as a critical starting material for cGMP peptide manufacturing, with documented use in the production of therapeutic peptides requiring controlled disulfide bridging.

Product Parameters

Why Cosperpharm?

Cosperpharm has been a trusted supplier of high-quality Fmoc-protected amino acids to peptide synthesis laboratories, CROs, and pharmaceutical manufacturers worldwide. We combine rigorous quality control with the supply flexibility that modern peptide discovery demands.

Quality that drives reproducible synthesis. In Fmoc SPPS, the purity of your building blocks directly determines the yield and purity of your final peptide. Our Fmoc-Cys(Acm)-OH, Fmoc-Trp(Boc)-OH, and Fmoc-Gly-OH are released only after comprehensive analytical testing, including HPLC purity verification, water content analysis (Karl Fischer), and optical rotation confirmation (where applicable). Every batch is fully traceable, with retention samples maintained in accordance with Cosperpharm quality procedures.

Documentation that supports your research. Peptide synthesis for preclinical studies and commercial production requires documentation you can trust. Every Cosperpharm shipment includes a batch-specific Certificate of Analysis (COA) detailing HPLC purity, chromatographic traceability, and physical characterization data. Stability summaries and custom quality agreements are available upon request for customers requiring extended documentation packages.

Supply that matches your scale. Whether you need 1g for initial method development, 100g for process validation, or kilogram quantities for commercial peptide production, Cosperpharm delivers. We maintain safety stock of all three Fmoc building blocks to support rapid turnaround. R&D quantities ship within 5–7 business days; bulk orders ship within 2–3 weeks.

Technical expertise in your corner. Our team has extensive experience in Fmoc SPPS across multiple therapeutic areas. We can advise on coupling conditions for sterically hindered amino acids, orthogonal deprotection strategies for disulfide-rich peptides, and best practices for handling moisture-sensitive Fmoc derivatives. With Cosperpharm, you get more than a supplier — you get a synthesis partner.

Global reach, transparent pricing. Cosperpharm ships to laboratories and manufacturing facilities worldwide, with full customs documentation included. Volume discounts apply at larger scales, and we communicate lead times upfront — no hidden fees, no unexpected delays. Contact us to discuss how Cosperpharm can support your next peptide synthesis campaign.

Safety & Handling – What You Need to Know

This compound carries multiple hazard classifications:

Required Protective Measures:

 Eyes: Safety goggles (mandatory).

 Skin: Chemicalresistant gloves (nitrile). If you have a history of skin allergies, take extra precautions due to skin sensitizer classification.

 Respiratory: Use in a fume hood. Avoid breathing dust.

 First aid:

1. Eye contact – rinse with water for 15 min (S26).

2. Skin contact – wash with soap and water. If rash or irritation develops, seek medical advice (skin sensitizer).

3. Inhalation – move to fresh air.

 Storage: Keep container tightly sealed in a dry place at room temperature. Store away from ignition sources (combustible solid). Avoid contact with strong mineral acids (releases irritating free monoester).

 Disposal: Collect as chemical waste. WGK 1 indicates low water hazard, but best practice is not to flush down drains.

Quality Assurance at Cosperpharm

Each batch undergoes:

 Gas chromatography (GC) – purity ≥97.0%

 Non‑aqueous titration – purity ≥97.0%

 Refractive index – confirmatory analysis

 ¹H NMR – structural verification

 Appearance – colorless to light yellow to light orange clear liquid

A comprehensive COA, MSDS (with full GHS information), and certificate of origin accompany every shipment.

Contact us

Struggling with low yields in your disulfide-rich peptide project? Cosperpharm’s Fmoc-Cys(Acm)-OH is backed by rigorous analytical release and batch-to-batch consistency. Our technical team understands the challenges of Acm deprotection and sequential disulfide formation — we are ready to share practical tips for Hg(II)/I₂ cleavage and on-resin cyclization. Request a quote, a custom packing size, or a DMF-ready documentation package today. Reach out to Cosperpharm — let’s get your peptide folded correctly.