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| Product Name | Fmoc-Glu(OtBu)-OH |
|---|---|
| Synonyms | Nα-Fmoc-L-glutamic acid γ-tert-butyl ester; Fmoc-L-glutamic acid 5-tert-butyl ester |
| Catalog No. | AS1318 |
| CAS Number | 71989-18-9 |
| Molecular Formula | C24H27NO6 |
| Molecular Weight | 425.47 g/mol |
| SMILES | CC(C)(C)OC(=O)CCC@HC(O)=O |
| Storage Temperature | ≤25°C, protect from light |
| Appearance | White powder |
| Melting Point | 80–100°C |
| Specific Rotation | -8.5° ± 2° (C=1 in MeOH) |
| Functional Groups | Fmoc-protected α-amino group; tert-butyl-protected γ-carboxyl group; free α-carboxylic acid |
| Primary Application | Fmoc solid-phase peptide synthesis (SPPS) |
Product Overview
Fmoc-Glu(OtBu)-OH is the standard protected L-glutamic acid building block used for incorporation of glutamate residues in Fmoc-based solid-phase peptide synthesis (SPPS).
The α-amino group is protected with Fmoc, while the side-chain γ-carboxyl group is protected as an acid-labile tert-butyl ester (OtBu). The α-carboxyl group remains available for activation and coupling to the growing peptide chain.
During final TFA cleavage and global deprotection, the OtBu group is removed to regenerate the native glutamic acid side chain.
This protecting-group arrangement makes Fmoc-Glu(OtBu)-OH suitable for routine synthesis of Glu-containing peptides, acidic peptides, peptide libraries and modified research sequences. Sigma also specifies the compound for Fmoc-SPPS and peptide synthesis.
Applications in Peptide Synthesis
| Application | Role of Fmoc-Glu(OtBu)-OH |
|---|---|
| Fmoc-SPPS | Standard building block for incorporation of L-glutamic acid |
| Acidic Peptides | Introduces a negatively charged Glu side chain after deprotection |
| Peptide Libraries | Supports parallel preparation of Glu-containing sequences |
| Modified Peptides | Compatible with many terminal and side-chain modification strategies |
| SAR Studies | Enables systematic incorporation or replacement of glutamate residues |
| Long Peptides | Suitable for conventional multi-cycle Fmoc/tBu synthesis |
| Custom Peptide Synthesis | Used in research-scale linear and modified peptide production |
Fmoc-Glu(OtBu)-OH in Fmoc-SPPS
Fmoc-Glu(OtBu)-OH is coupled through its free α-carboxyl group. After coupling, base-mediated Fmoc removal exposes the α-amino group for the next synthesis cycle, while the γ-carboxyl group remains protected.
During final acidic cleavage, the OtBu group is removed, generating the native glutamate side-chain carboxylic acid.
This is the conventional orthogonal protection strategy used for glutamic acid in Fmoc/tBu chemistry.
For a broader synthesis overview, see Solid-Phase Peptide Synthesis (SPPS): A Practical Guide.
Fmoc-Glu(OtBu)-OH vs Fmoc-Glu-OtBu
These two names should not be treated as interchangeable.
Fmoc-Glu(OtBu)-OH protects the side-chain γ-carboxyl group, leaving the α-carboxyl group available for conventional peptide-chain coupling.
By contrast, Fmoc-Glu-OtBu refers to a different protection pattern in which the α-carboxyl group is protected and the side-chain carboxyl group remains available.
This distinction becomes especially important in synthesis involving:
γ-glutamyl linkages
branched peptides
side-chain conjugation
peptide–drug linkers
glutamate-containing branching architectures
Alan Scientific practical view: the protecting-group pattern should always be selected according to the bond that must be formed. For conventional α-peptide synthesis, Fmoc-Glu(OtBu)-OH is normally the appropriate building block.
Glutamate and Peptide Properties
After deprotection, glutamate introduces a carboxylic-acid side chain that is typically negatively charged near physiological pH.
As a result, Glu residues can influence:
aqueous solubility
electrostatic protein interactions
peptide net charge
chromatographic retention
secondary structure
receptor-binding behavior
Recent peptide-design literature continues to identify Asp and Glu as important residues for increasing peptide hydrophilicity through hydrated carboxylate side chains.
This means the role of Fmoc-Glu(OtBu)-OH extends beyond simply assembling a sequence: glutamate placement can materially influence the properties of the final peptide.
Product Documents
A Safety Data Sheet (SDS / MSDS) is available for this product to support laboratory handling, storage and safety assessment.
📎 MSDS_Fmoc-Glu(OtBu)-OH_AS1318.pdf
Related Technical Resources
Explore additional Standard Fmoc-Amino Acids.
Learn more about Amino Acids & Peptide Building Blocks.
For complete peptide projects, visit Custom Peptide Synthesis.
Why Source Peptide Building Blocks from Alan Scientific?
Alan Scientific supplies protected amino acids and specialized peptide building blocks for research applications, with competitive pricing, flexible quantities and technical support for peptide synthesis.
Individual building blocks can also be integrated directly into Custom Peptide Synthesis projects.
Research Use Only