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Fmoc-D-Phe-D-Phe-OH is an N-Fmoc-protected all-D diphenylalanine fragment with a free C-terminal carboxyl group. Both phenylalanine residues are D-configured, giving the molecule the same elemental composition as an L,L analog but a different stereochemical identity.
The Fmoc-D-Phe-D-Phe motif is relevant to two distinct research intents: it can be used as a protected D,D dipeptide fragment for peptide synthesis, and D-Phe-D-Phe-containing aromatic motifs have also been studied in self-assembling peptide materials. Those two uses should not be conflated; terminal chemistry and the rest of the sequence strongly influence material behavior.
Product Information
| Product Name | Fmoc-D-Phe-D-Phe-OH |
| Catalog No. | AS4147 |
| CAS No. | 398518-23-5 |
| Molecular Formula | C33H30N2O5 |
| Molecular Weight | 534.60 g/mol |
| Chemical Identity | Fmoc-D-Phe-D-Phe-OH; N-Fmoc-D-phenylalanyl-D-phenylalanine |
| Building Block Type | Fmoc-protected all-D aromatic dipeptide |
| Primary Applications | D-peptide synthesis, aromatic self-assembly research, proteolytic-stability studies and protected fragment coupling |
Why the D,D Configuration Matters
D-amino-acid substitution is widely used to study protease resistance, stereochemical recognition and altered peptide conformations. Alan's D-form amino acid portfolio provides the broader monomer context. For stepwise assembly of D-Phe-containing sequences, Fmoc-D-Phe-OH is the corresponding standard monomer.
Self-Assembly: Motif Matters, but Terminal State Matters Too
Aromatic Fmoc-Phe-Phe motifs are well known in supramolecular peptide research, and D-Phe-D-Phe derivatives have been used to increase proteolytic stability in self-assembled systems. However, results from amidated or extended Fmoc-D-Phe-D-Phe derivatives should not be transferred automatically to this free C-terminal acid. Charge state, pH, concentration, solvent and terminal modification can all change assembly behavior.
Mass Cannot Prove D,D Stereochemistry
Fmoc-D-Phe-D-Phe-OH and the corresponding L,L enantiomer have the same formula and nominal mass. LC-MS therefore confirms composition but not chirality. We consider lot-specific stereochemical documentation essential when the product is used for matched D/L comparisons or as an analytical intermediate.
Procurement and QC Considerations
Confirm CAS 398518-23-5, formula C33H30N2O5, MW 534.60 g/mol, D,D configuration, N-terminal Fmoc protection and free C-terminal acid. For self-assembly work, also define purity, counterion/solvent history and handling conditions because small compositional differences can affect supramolecular behavior.
For partial-D or all-D sequences, Alan's custom synthesis of D-amino-acid and all-D peptides supports sequence-specific purity and QC requirements.
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 is Fmoc-D-Phe-D-Phe-OH used for?
It is used as an all-D aromatic dipeptide fragment in D-peptide synthesis and as a research motif in self-assembly and proteolytic-stability studies.
Can LC-MS distinguish the D,D product from an L,L enantiomer?
No. Enantiomers have the same molecular mass, so stereochemical identity requires additional documentation or chiral analysis.
Will every Fmoc-D-Phe-D-Phe derivative form the same hydrogel or nanofiber?
No. Terminal groups, pH, concentration, solvent and appended residues can strongly change self-assembly behavior.
Related Technical Resources
For aromatic side-chain chemistry beyond D stereochemistry, see phenylalanine and tryptophan building blocks. For design context, review how noncanonical and D residues expand peptide design space.