Fmoc-Lys(Mtt)-OH

Fmoc-Lys(Mtt)-OH is widely recognized as the premier building block for side-chain to side-chain cyclic peptide synthesis and the construction of oligolysine cores. When using Fmoc-Lys(Mtt)-OH, researchers can selectively deprotect the lysine side chain without disturbing the Fmoc group on the growing peptide backbone, enabling chemoselective on-resin modification. Moreover, Fmoc-Lys(Mtt)-OH is a key component in the synthesis of multiple antigenic peptides (MAPs) and template-assembled synthetic proteins (TASPs), where it serves as a scaffold core for assembling branched architectures. The strategic application of Fmoc-Lys(Mtt)-OH has also proven invaluable in the creation of peptide-immobilized magnetic beads for biomedical applications, including the assessment of skin sensitization using chromophore-based reactivity assays.

Product Parameters

Product Advantages

1. Orthogonal Protecting Group Strategy

The dual protection system of Fmoc-Lys(Mtt)-OH is its defining feature. The Fmoc group (base-labile, removed with 20% piperidine in DMF) and the Mtt group (very acid-labile, removed with as low as 1% TFA in DCM) are fully orthogonal to each other and to most common protecting groups (tBu, Boc, Pbf, Trt). This orthogonality enables stepwise on-resin deprotection and modification of the lysine side chain without compromising the main chain assembly.

2. Enables Branched and Cyclic Peptide Synthesis

The ability to selectively deprotect the ε-amine of lysine using Fmoc-Lys(Mtt)-OH allows for the construction of branched peptides (where multiple peptide chains are grafted from a single lysine core) and side-chain to side-chain cyclic peptides (where the ε-amine is coupled to a side-chain carboxylate on a neighboring residue). This is the foundation for generating multiple antigenic peptides (MAPs) and template-assembled synthetic proteins (TASPs).

3. Compatible with Standard SPPS Protocols

Fmoc-Lys(Mtt)-OH is fully compatible with standard automated Fmoc SPPS workflows. Its solubility in DMF and DMSO ensures seamless integration into your existing synthesis protocols. The coupling kinetics are comparable to standard Fmoc-amino acids, requiring no special optimization for most sequences.

4. Broad Application in Peptide Engineering

From the synthesis of peptide-immobilized magnetic beads for diagnostic applications to the development of cyclic peptide therapeutics, Fmoc-Lys(Mtt)-OH is a versatile tool in the peptide chemist‘s arsenal. It has been successfully employed in the synthesis of reactive peptide crosslinkers via selective on-bead deprotection of Mtt and Fmoc groups.

5. Superior Synthetic Efficiency

Documented synthetic routes for Fmoc-Lys(Mtt)-OH achieve yields of >80% and purity >99%, demonstrating that high-quality material is accessible. Cosperpharm’s manufacturing process is designed to minimize dipeptide formation, free amino acids, and acetic acid impurities, ensuring that your synthesis proceeds with maximum fidelity.

 FAQ

Q1: What is the difference between Mtt and Mmt protecting groups on lysine?

A: Mtt (4-methyltrityl) and Mmt (4-methoxytrityl) are both very acid-labile protecting groups for the lysine ε-amine. The Mtt group is cleaved slightly more readily than Mmt under mild acidic conditions. Fmoc-Lys(Mtt)-OH is the more commonly used derivative for standard SPPS applications requiring side-chain deprotection with 1–3% TFA in DCM.

Q2: How do I selectively remove the Mtt group without affecting Fmoc?

A: The Mtt group on Fmoc-Lys(Mtt)-OH can be selectively removed with as low as 1% TFA in DCM. Standard deprotection cocktails include 1% TFA/DCM (2–5 minutes, repeated), or a mixture of DCM/HFIP/TFE/TES (6.5:2:1:0.5) for more acid-sensitive sequences. These conditions leave the Fmoc group intact, allowing subsequent chain elongation.

Product Quality Assurance

Cosperpharm has established a comprehensive quality assurance system for Fmoc-Lys(Mtt)-OH that meets the rigorous expectations of pharmaceutical peptide synthesis and research applications:

Thorough analytical characterization. Each batch undergoes multi‑technique analytical release testing: HPLC purity (≥98.0% industrial grade, with full chromatographic traceability), melting point verification (141–143 °C), optical rotation confirmation ([α]²⁰ᴅ = +3.36°, c=1 in THF), water content determination (Karl Fischer <1.0%), free amino acids (<0.1%), and D‑enantiomer analysis (<0.1%).

Full batch traceability with retention samples. From raw material procurement through Mtt-Cl coupling, Fmoc protection, purification, drying, and final packaging, every step is fully documented and traceable. Each batch receives a unique lot number with sufficient retention samples maintained.

Stability monitoring program. Cosperpharm conducts ongoing stability studies under recommended storage conditions (–20 °C and 4 °C). Stability summaries are updated regularly, with full data packages available to support customer research.

Documentation for regulatory submission. Every shipment includes a Certificate of Analysis (COA) with batch‑specific purity and characterization data, a Material Safety Data Sheet (SDS), and customs documentation. For customers preparing regulatory filings or requiring enhanced documentation, DMF‑ready packages, method validation reports, and custom quality agreements are available upon request.

Customer‑initiated quality audits. Qualified customers are welcome to audit Cosperpharm‘s manufacturing, quality control, and documentation facilities. ISO compliance documentation is available upon request.

Contact Us

Need a reliable source of Fmoc-Lys(Mtt)-OH for your next cyclic or branched peptide synthesis? Contact Cosperpharm today for competitive pricing, technical support, and fast global delivery.