D-Phenylalanine

Technical Specifications

Product Description & Scientific Applications

D-Phenylalanine (D-Phe; H-D-Phe-OH) is the non-proteinogenic D-enantiomer of phenylalanine and an aromatic D-amino acid building block for peptide chemistry, asymmetric synthesis, and biocatalysis. Because chymotrypsin and other L-stereoselective proteases process only L-configured residues, placing D-Phe at a cleavage site can raise a peptide's proteolytic resistance while preserving the aromatic side chain that supports hydrophobic binding and conformational bias. Its fixed configuration and UV-detectable aromatic chromophore suit it to D-amino acid scans and to mechanistic studies of D-amino-acid-transforming enzymes.

Protease-resistant residue. Chymotrypsin's hydrophobic S1 pocket favours L-Phe, Tyr, and Trp at P1; inverting the α-carbon to D-Phe disrupts productive substrate alignment without removing the aromatic group. It is used in D-amino acid scans, peptidomimetics, and cyclic protease-resistant scaffolds, where a D-residue paired with proline templates a type II′ β-turn. It occurs in non-ribosomal cyclic decapeptides — gramicidin S, cyclo(Val-Orn-Leu-D-Phe-Pro)₂, whose two D-Phe–Pro turns close the antiparallel β-sheet, and the related tyrocidine D-Phe–Pro motif. In gramicidin S biosynthesis the GrsA module activates L-Phe and epimerises the thioester-bound intermediate before chain transfer.

Chiral building block. The fixed (R)-configuration transfers stereochemistry predictably into downstream intermediates; after N- and C-terminal protection, protected D-Phe derivatives are built into peptide and small-molecule scaffolds, chiral auxiliaries, and resolving agents requiring the non-natural configuration.

Biocatalysis probe. A substrate and mechanistic probe for D-amino acid oxidase (DAAO, FAD-dependent) and PLP-dependent D-amino acid transaminases, used to probe stereoselectivity, substrate scope, kinetic mechanism, and active-site recognition. For human DAAO, bulky hydrophobic D-amino acids — D-Phe, D-DOPA, D-Tyr, D-Trp — are among the most reactive, varying with enzyme source and engineered variant. It is also a DAAO substrate in immobilised-enzyme reactors and in amino-acid deracemisation, which couples stereoselective enzymatic oxidation with non-selective chemical reduction of the imino acid.

Hydroxyl-radical probe. A specific •OH trap in chemical, enzymatic, cellular, and intact-organ systems: aromatic hydroxylation yields the three regioisomers o-, m-, and p-tyrosine, resolved by HPLC with electrochemical or fluorescence detection. Because phenylalanine hydroxylase is L-selective, tyrosines from administered D-Phe report non-enzymatic radical attack rather than enzymatic Phe→Tyr conversion — used in oxidative-stress, ex vivo organ-perfusion and reperfusion, and redox-signalling studies.

Other uses. Reference standard for enantioselective HPLC and capillary-electrophoresis separations; probe for stereoselective recognition by the system-L transporter LAT1; substrate in biocatalytic stereoinversion and deracemisation; certified-reference/calibration standard for chromatographic (LC–CD) quantification of amino acid enantiomers.

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