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(S)-2-Amino-3-hydroxy-2-methylpropanoic acid is the free amino acid commonly called (S)-α-methylserine. It combines a serine-like hydroxymethyl side chain with an additional methyl group on the α-carbon, creating a more substituted backbone center than ordinary serine.
This product is supplied as the free amino acid rather than as a fully protected SPPS monomer. Its value lies in derivatization and route design: the amino group, hydroxyl group and carboxyl group can be protected or functionalized according to the intended chemistry.
Product Information
| Product Name | (S)-2-Amino-3-hydroxy-2-methylpropanoic acid |
| Catalog No. | AS2128 |
| CAS No. | 16820-18-1 |
| Molecular Formula | C4H9NO3 |
| Molecular Weight | 119.12 g/mol |
| Chemical Identity | (S)-α-methylserine |
| Building Block Type | Free noncanonical α-methyl amino acid |
| Primary Applications | Noncanonical amino-acid derivatization, α-methylserine peptide design and chiral synthesis |
How α-Methylserine Differs from Serine
Serine contains an α-hydrogen, while α-methylserine contains an additional α-methyl group. This changes local steric demand and can reduce conformational freedom after incorporation into a peptide. The hydroxymethyl side chain is retained, so the residue still provides a polar alcohol functionality. Our article on noncanonical and α-methyl amino acids in peptide discovery discusses why this kind of backbone modification is used in SAR.
Protection Strategy Comes Before SPPS
The supplied material has free amino, carboxyl and hydroxyl functionality. Standard Fmoc-SPPS normally requires Nα protection and may also require side-chain hydroxyl protection depending on the sequence and cleavage strategy. Fmoc-OSu is one established reagent class used to prepare Fmoc-protected amino-acid derivatives when substrate compatibility is appropriate.
Why Matched Analog Design Is More Informative
α-Methylation can improve or reduce biological performance depending on position. We therefore view α-methylserine as a deliberate conformational probe rather than a universally beneficial replacement for serine. A useful experimental design compares the modified peptide with the parent sequence and, when relevant, other stereochemical or side-chain controls.
Procurement and QC Considerations
Confirm CAS 16820-18-1, C4H9NO3, MW 119.12 g/mol and S configuration. If the material will be derivatized before peptide synthesis, assay, water content and stereochemical identity can influence downstream protection and coupling performance.
Product Documents
A Safety Data Sheet (SDS / MSDS) is available for this product to support laboratory handling, storage and safety assessment.
MSDS_S-2-Amino-3-hydroxy-2-methylpropanoic-acid_AS2128
Certificates of Analysis (COAs) are batch-specific. Please contact us to request the COA for your product, and we will provide it by email.
Frequently Asked Questions
Is this product the same as serine?
No. It contains an additional methyl substituent at the α-carbon.
Can the free amino acid be inserted directly into routine Fmoc-SPPS?
Normally an appropriate Nα protecting group is required first, and hydroxyl protection may also be needed depending on the route.
Why use α-methylserine in peptide design?
It combines a serine-like hydroxyl side chain with increased backbone substitution, allowing researchers to probe conformational and proteolytic effects.
Related Technical Resources
For preparation or incorporation of a protected α-methylserine derivative into a sequence, see our noncanonical peptide synthesis capabilities.