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Fmoc-D-Abu-OH is the Fmoc-protected D-enantiomer of 2-aminobutyric acid (Abu). Abu is a compact nonproteinogenic α-amino acid whose ethyl side chain is one carbon longer than alanine's methyl group.
The D configuration adds a second design variable: side-chain size changes from Ala to Abu, while stereochemistry is inverted relative to the common L-amino-acid framework. Researchers planning broader D-residue comparisons can explore Alan Scientific's D-Form Amino Acids.
Product Information
| Product Name | Fmoc-D-Abu-OH |
| Catalog No. | AS2024 |
| CAS No. | 170642-27-0 |
| Molecular Formula | C19H19NO4 |
| Molecular Weight | 325.36 g/mol |
| Building Block Type | Fmoc-protected D-2-aminobutyric acid |
| Primary Applications | D-amino-acid peptide synthesis; Abu substitutions; protease-stability studies; stereochemical SAR; Fmoc-SPPS |
Why Abu Is a Useful Small Hydrophobic Substitution
Abu provides a modest increase in hydrophobic bulk relative to alanine without introducing branching at the β-carbon. This can make it useful for probing a binding pocket that tolerates slightly more side-chain volume while avoiding a large aromatic or branched substitution.
D Stereochemistry Can Change More Than Protease Stability
D residues can reduce recognition by some proteases, but they can also change local backbone conformation and target binding. A D-Abu substitution should therefore be interpreted as a stereochemical perturbation, not only as a stability modification.
Fmoc Compatibility
The α-amino group is Fmoc-protected and the carboxyl group is available for peptide coupling. Standard Fmoc-SPPS concepts apply, although the final sequence still determines coupling efficiency and purification behavior.
Procurement and QC
Confirm CAS 170642-27-0, formula C19H19NO4, MW 325.36 g/mol, and D/(2R) stereochemistry. The L and D forms have identical molecular mass, so mass spectrometry cannot establish enantiomeric identity.
For matched L/D or Ala/Abu analog series, Alan Scientific can keep synthesis and analytical conditions aligned through custom peptide synthesis.
Product Documents
A Safety Data Sheet (SDS / MSDS) is available for this product to support laboratory handling, storage and safety assessment.
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
What does Abu stand for?
Abu commonly denotes 2-aminobutyric acid.
How is Abu different from alanine?
Abu has an ethyl side chain rather than alanine's methyl side chain.
Can LC-MS distinguish D-Abu from L-Abu?
No. Enantiomers have the same molecular mass.
Related Technical Resources
Read how noncanonical residues expand peptide design