4-Methy-L-Phenylalanine is a naturally occurring amino acid derivative classified as a phenylalanine analogue, featuring a benzyl side chain bearing a methyl substituent at the 4-position. The molecule contains a free amino group and a free carboxyl group, with stereochemistry indicated as L-form in the name, and the aromatic side chain provides a hydrophobic, π-interacting functionality that can influence peptide conformations and intermolecular contacts. As an unprotected amino acid, it is used as a building block in peptide synthesis and structure-activity or binding studies where incorporation of a methyl-substituted aromatic residue is used to probe steric and electronic effects.
CAT No: CP15801
CAS No:1991-87-3
Synonyms/Alias:1991-87-3;L-4-Methylphenylalanine;4-Methyl-L-phenylalanine;H-Phe(4-Me)-OH;4-Methylphenylalanine;(S)-2-Amino-3-(p-tolyl)propanoicacid;(2S)-2-amino-3-(4-methylphenyl)propanoicacid;L-4-METHYLPHE;Phenylalanine,4-methyl-;L-4-ME-PHE-OH;SBB064583;(S)-2-amino-3-p-tolylpropanoicacid;(S)-2-AMINO-3-P-TOLYL-PROPIONICACID;7758-37-4;D-4-Methylphenylalanine;4-Methy-L-Phenylalanine;AC1Q2JKR;(S)-4-Methylphenylalanine;AC1L46HI;4-METHYL-L-PHE-OH;SCHEMBL44872;L-PHE(4-ME)-OH;H-L-PHE(4-ME)-OH;P-METHYL-L-PHENYLALANINE;CTK2H7427
4-Methy-L-Phenylalanine is a chiral, non-proteinogenic phenylalanine analog featuring a methyl substituent on the aromatic ring, which makes it a useful aromatic side-chain variant for structure-property studies and peptide design. As an L-configured amino acid building block, it provides a stereochemically defined amino acid backbone while introducing additional steric and hydrophobic character at the phenyl ring. Researchers use this compound to probe how aromatic substitution patterns influence peptide conformation, binding-site interactions, and downstream physicochemical behavior in chemical biology and medicinal chemistry workflows.
1. Peptide Building Block
4-Methy-L-Phenylalanine is used as an amino acid building block for custom peptide synthesis, including solution-phase and solid-phase workflows, where aromatic side-chain substitution is needed to tune local sterics and hydrophobicity. Peptide chemists incorporate this residue into short peptide sequences and peptidomimetic scaffolds to evaluate how ring methylation affects folding propensity, side-chain packing, and interaction patterns relative to unsubstituted phenylalanine. The defined L-stereochemistry supports consistent residue geometry in peptide libraries and SAR-focused analog series, while the substituted phenyl ring provides a practical handle for comparing aromatic substitution effects across closely related constructs.
2. Medicinal Chemistry SAR Studies
4-Methy-L-Phenylalanine is frequently selected in medicinal chemistry for structure-activity relationship (SAR) development of peptidomimetic and peptide-like small molecules where aromatic substitution can modulate binding interactions and overall molecular shape. Medicinal chemistry teams use this residue to generate analog panels that systematically vary aromatic substitution while keeping the amino acid backbone consistent, enabling clearer interpretation of how added methyl sterics and hydrophobic character influence structure-property trends. This approach is commonly applied in lead optimization programs for receptor-binding ligands, enzyme inhibitors, and other non-covalent binding scaffolds that rely on aromatic contacts in the binding pocket.
3. Protein Engineering Probes
4-Methy-L-Phenylalanine is used in chemical protein engineering and protein chemistry workflows to introduce an aromatic ring-modified residue into peptide segments or engineered protein constructs for mechanistic studies of side-chain recognition. Researchers employ such non-natural aromatic amino acid analogs to create controlled perturbations at specific interaction hotspots, supporting comparative studies of how aromatic substitution influences local microenvironment effects, such as packing and hydrophobic contact patterns. This makes the compound relevant for developing site-specific probes and for constructing protein/peptide variants used in binding studies, interaction mapping, and structural characterization efforts where precise residue identity matters.
4. Analytical Reference Standards
4-Methy-L-Phenylalanine serves as a defined reference material for analytical method development and mass spectrometry workflows that require aromatic amino acid standards with a distinct substitution pattern. Analytical chemists use it to help verify chromatographic behavior and to support identification and quantification strategies when substituted phenylalanine analogs appear as synthetic impurities, degradation products, or designed residues in peptide samples. Because the compound is a single, stereochemically defined amino acid analog, it is also useful for building calibration and confirmation sets in LC-MS-based analysis of peptide libraries and related chemical biology samples.
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