4-Phenyl-L-Phenylalanine is a non-natural, aromatic amino acid derivative featuring an L-amino acid backbone bearing a phenyl substituent at the 4-position of the side chain, yielding a diaryl side chain with increased hydrophobic and π-interaction character. The molecule contains a free amino group and a free carboxyl group on the α-carbon, with the stereochemistry specified as L and the side chain functionalization replacing the typical benzyl group environment of phenylalanine with an additional phenyl ring. As a substituted phenylalanine analogue, it can be used in peptide synthesis and structure-activity or binding studies to probe how extended aromatic substitution patterns affect peptide conformation, receptor/target interactions, and physicochemical properties.
CAT No: CP16301
4-Phenyl-L-Phenylalanine is an L-amino acid bearing an extended hydrophobic side chain formed by a biphenyl motif, making it a useful non-proteinogenic building block for structure-driven peptide and peptidomimetic design. Its stereochemistry is defined at the alpha-carbon, and the molecule presents the standard amino acid functionality that enables downstream conversion into peptide-coupling formats or incorporation into synthetic sequences. Owing to the bulky aromatic character, this residue is frequently selected to modulate conformation, hydrophobic packing, and aromatic interactions in medicinal chemistry and chemical biology workflows.
1. Peptidomimetic Building Block
4-Phenyl-L-Phenylalanine is used by medicinal chemistry and peptide chemistry groups to introduce a highly hydrophobic, aromatic-rich side chain into peptidomimetics and modified peptide scaffolds. Researchers incorporate this residue to tune local structure through π-π interactions and steric effects, supporting structure-activity relationship studies where aromatic surface area and packing are key variables. In practice, it is commonly handled as a protected or activated amino acid derivative for sequence assembly, enabling controlled placement within short bioactive peptides, receptor-binding motifs, or enzyme inhibitor fragments where enhanced aromatic character is desired.
2. Hydrophobic SAR Studies
4-Phenyl-L-Phenylalanine supports structure-activity relationship (SAR) programs in small-molecule and peptide-conjugate development by providing a distinct aromatic side-chain handle that differs from standard phenylalanine. Chemical biology and medicinal chemistry teams use it to systematically compare how increased hydrophobicity and aromatic geometry influence binding-site complementarity, aggregation propensity, and overall physicochemical behavior of lead series. Because the residue contributes a larger, more conformationally demanding aromatic environment, it is often selected for analog generation in iterative optimization campaigns, including head-to-tail or side-chain modified peptide analogs used to probe interaction hypotheses.
3. Aromatic-Driven Protein Engineering
4-Phenyl-L-Phenylalanine is employed in protein engineering and protein design efforts where non-natural aromatic residues are introduced to strengthen hydrophobic cores or reinforce specific interaction networks within engineered proteins. Protein scientists and bioconjugation-focused labs use such residues to create or stabilize binding interfaces in peptide-derived domains, engineered binders, and scaffold proteins that rely on aromatic packing for structural integrity. The defined L-configuration and rigid biphenyl-like side chain help maintain consistent stereochemical placement during chemical incorporation into protein segments, supporting studies that map how aromatic substitution patterns affect folding behavior and complex formation in vitro.
4. Chemical Biology Probe Design
4-Phenyl-L-Phenylalanine is used in chemical biology for constructing peptide-based probes that require enhanced hydrophobic and aromatic character to achieve favorable interaction with target surfaces or binding pockets. Probe developers incorporate this residue into recognition elements to adjust affinity-driving features without changing the overall backbone composition, enabling more controlled comparisons across probe variants. In downstream workflows, the residue's aromatic-rich side chain can improve the stability of probe conformations and influence how the probe presents functional groups for labeling, immobilization, or assay readouts, making it a practical choice for designing structure-tuned binding probes and affinity capture peptides.
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