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| Product Name | Fmoc-Met-OH |
|---|---|
| Synonyms | Nα-Fmoc-L-methionine; Fmoc-L-methionine |
| Catalog No. | AS0730 |
| CAS Number | 71989-28-1 |
| Molecular Formula | C20H21NO4S |
| Molecular Weight | 371.45 g/mol |
| Appearance | White powder |
| Melting Point | 115–140°C |
| Specific Rotation | -28° ± 2° (C=1 in DMF) |
| Storage Temperature | Cool, dry place (≤25°C) |
| Side-Chain Protection | None required |
| Primary Application | Fmoc-SPPS |
Product Overview
Fmoc-Met-OH is the Fmoc-protected form of L-methionine, a sulfur-containing amino-acid building block used in Fmoc-SPPS.
Methionine contains a thioether side chain that normally requires no protecting group. Its major synthetic consideration is therefore not deprotection chemistry but oxidation control.
Applications in Peptide Synthesis
| Application | Role of Fmoc-Met-OH |
|---|---|
| Fmoc-SPPS | Standard L-methionine building block |
| Sulfur-Containing Peptides | Introduces a thioether side chain |
| Natural Peptides | Supports synthesis of native Met-containing sequences |
| SAR Studies | Allows evaluation of sulfur-containing hydrophobic residues |
| Peptide Libraries | Standard proteinogenic building block |
| Custom Peptides | Used in linear, cyclic and modified sequences |
Fmoc-Met-OH in Fmoc-SPPS
Fmoc-Met-OH does not normally require side-chain protection.
Its α-carboxyl group is activated for coupling, followed by routine Fmoc removal for further peptide elongation.
The main additional consideration is keeping the methionine sulfur in its desired thioether oxidation state.
Methionine Oxidation Is the Key Technical Issue
Methionine can oxidize to methionine sulfoxide during synthesis, cleavage, purification, handling or storage.
This transformation adds one oxygen atom and produces a characteristic +16 Da mass shift.
Oxidation risk can increase with:
oxidizing reagents
prolonged air exposure
peroxide contamination
harsh workup conditions
long storage under unfavorable conditions
For high-purity Met-containing peptides, preventing oxidation is generally preferable to attempting to remove oxidized peptide afterward.
Why Met Oxidation Matters in Final Peptide QC
Methionine sulfoxide can have different chromatographic retention and biological properties from the native peptide.
LC-MS can often reveal the +16 Da species, making oxidation easier to identify than many isomeric impurities.
Alan Scientific practical view: for Met-containing peptides, final QC should consider oxidation state as part of peptide identity and purity—not simply whether the theoretical parent mass is present.
Product Documents
A Safety Data Sheet (SDS / MSDS) is available for this product to support laboratory handling, storage and safety assessment.
Related Technical Resources
Explore Standard Fmoc-Amino Acids.
Read Amino Acids & Peptide Building Blocks.
For synthesis and QC support, see Custom Peptide Synthesis.
Why Source Peptide Building Blocks from Alan Scientific?
Alan Scientific supplies protected amino acids and peptide building blocks for research peptide synthesis, supported by technical expertise in synthesis, purification and analytical QC.
Research Use Only