H-[15N]Phe-OH

H-[15N]Phe-OH is an isotopically labeled phenylalanine where the alpha-amino acid backbone is present as the free amino acid (NH2 and CO2H) and the nitrogen atom is enriched with 15N, enabling mass-shift tracking in mechanistic and structural studies. The molecule retains the stereochemical identity of phenylalanine at the chiral alpha carbon, with a hydrophobic benzyl side chain that participates in typical amino acid recognition and peptide coupling chemistries. The carboxylic acid and amino functionality support standard protection-group strategies for peptide synthesis and allow conversion into activated derivatives for downstream labeling workflows. The 15N label provides a direct handle for NMR, MS, and isotope-resolved experiments, making H-[15N]Phe-OH a practical chiral amino acid intermediate for biochemical research and peptide science.

1. Isotope Labeling Studies

H-[15N]Phe-OH is used in isotope-resolved biochemical research and analytical chemistry where incorporation of a 15N-labeled nitrogen enables unambiguous detection of phenylalanine-derived fragments by mass spectrometry and isotope-sensitive NMR. The free amino acid functional groups facilitate conversion to protected forms or activated coupling partners while preserving the chiral alpha-center required for stereochemically defined incorporation. The benzyl side chain supports placement into peptide contexts where isotope tracking can follow specific residues through digestion, binding assays, or conformational analyses. The resulting labeled peptides or metabolites can serve as reference materials for mechanistic studies of backbone dynamics, translation-related workflows, or protein turnover measurements.

2. Peptide Synthesis Incorporation

H-[15N]Phe-OH is suitable for peptide building block preparation and solid-phase or solution-phase peptide synthesis workflows that require stereochemically consistent phenylalanine incorporation with an NMR/MS-detectable 15N label. The amino and carboxyl groups allow standard orthogonal protection and activation strategies, such as N-protection and carboxyl activation, to control chemoselectivity during chain elongation. The side-chain benzyl group is compatible with common peptide synthesis conditions and can be retained as-is when building peptides that model hydrophobic interactions. The 15N-enriched nitrogen becomes part of the peptide backbone amide, supporting residue-specific assignment in structural characterization and enabling isotope-guided interpretation of peptide conformation or aggregation behavior.

3. Protein Engineering Tracing

H-[15N]Phe-OH is applied in protein engineering and chemical biology experiments that benefit from residue-level tracing of phenylalanine incorporation into peptides, protein fragments, or engineered constructs. The labeled amino acid can be used to generate defined isotopic patterns that help map interaction interfaces, monitor conformational changes, or distinguish phenylalanine-containing segments in complex mixtures. The preserved chiral center ensures that the labeled residue maintains the stereochemical features recognized by peptide assembly chemistries and binding motifs. The downstream labeled biomolecules can be employed as analytical probes for studying folding pathways, ligand-induced structural rearrangements, or backbone-level dynamics using isotope-sensitive readouts.

4. Bioconjugation Chemistry

H-[15N]Phe-OH can be utilized in bioconjugation and biomolecule modification programs where labeled amino acid residues are incorporated into peptide linkers or functional tags for tracking conjugate formation. The presence of both amino and carboxyl groups supports conversion into coupling-ready intermediates that can be attached to amine-reactive or carboxyl-reactive partners while maintaining the 15N label within the linker backbone. The benzyl side chain helps maintain hydrophobic character and can influence linker conformation in conjugates used for analytical or binding studies. Labeled conjugates derived from H-[15N]Phe-OH may serve as standards for quantifying conjugation efficiency, mapping labeling sites, or following conjugate stability under analytical conditions.

5. Process Chemistry Intermediate

H-[15N]Phe-OH is relevant to fine chemical synthesis and process-oriented preparation of isotopically labeled amino acid derivatives used as inputs for downstream pharmaceutical research materials and biochemical instrumentation standards. The free amino acid functionality supports scalable derivatization into protected amino acid intermediates and activated esters or coupling partners, enabling controlled manufacturing of labeled peptide building blocks. The stereochemical integrity at the alpha carbon and the stable 15N label help maintain consistency across batch-to-batch preparations for reproducible analytical readouts. The compound's role as a chiral isotopic precursor supports reliable construction of labeled scaffolds used in isotope-resolved method development, library preparation, and synthetic route validation.

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