4-Carboxy-DL-tryptophan is a tryptophan-derived amino acid featuring an indole-containing aromatic side chain bearing an additional carboxyl group at the 4-position, classifying it as a non-standard, dicarboxylated amino acid analogue. The molecule contains both an amino functional group and a carboxylic acid group on the α-carbon, and its "DL" designation indicates a racemic mixture of stereoisomers at the chiral center while retaining the indole ring's nitrogen and π-system for aromatic interactions. As a chemically modified tryptophan analogue, it is used in peptide and amino acid derivative synthesis and in structure-property studies where the extra side-chain carboxyl functionality provides an additional site for salt formation, hydrogen bonding, and electrostatic modulation in biomolecular scaffolds.
CAT No: CP24603
4-Carboxy-DL-tryptophan is a DL mixture of D-tryptophan bearing an additional carboxyl group on the indole ring, providing a distinct, more acidic aromatic side-chain than standard tryptophan. This amino acid is typically used as a chemically defined building block for analytical method development and for preparing tryptophan-derived standards where indole carboxylation state matters. Its zwitterionic character and extra carboxyl functionality also make it useful for probing retention, derivatization, and ionization behavior in LC-MS workflows.
1. Analytical Standards Preparation
4-Carboxy-DL-tryptophan is used to generate chemically accurate reference materials for chromatography and mass spectrometry assays that distinguish indole-carboxylated tryptophan species from canonical tryptophan. Analytical chemists and metabolomics groups rely on this compound to evaluate derivatization efficiency, monitor ion-pairing or pH-dependent retention, and confirm expected mass-to-charge responses for indole-containing amino acid derivatives. The presence of both an amino acid carboxyl group and the additional indole carboxyl group supports robust, reproducible behavior during sample prep and instrument calibration, particularly when method performance depends on differentiating closely related tryptophan analogs.
2. LC-MS Metabolomics Method Development
4-Carboxy-DL-tryptophan serves as a practical reference for developing and validating LC-MS methods targeting tryptophan-related metabolites and indole-modified amino acid profiles. Researchers developing targeted panels use it to optimize chromatographic conditions and to assess how extra acidity on the indole ring affects peak shape, adduct formation, and fragmentation patterns under common electrospray conditions. Because it is supplied as a defined DL mixture, it is frequently chosen when the analytical goal is to quantify or qualify the presence of the indole-carboxylated motif without requiring stereospecific discrimination at the instrument level.
3. Peptide and Peptidomimetic Building Block
4-Carboxy-DL-tryptophan is applied as an amino acid building block for synthesizing peptides and peptidomimetic structures that incorporate an indole-carboxylated tryptophan residue. Medicinal chemistry and peptide chemistry teams use it to explore how an additional carboxyl group on the aromatic side chain influences local charge distribution, conformational preferences, and chemical stability of peptide analogs. In downstream workflows, the extra acidic functionality can be leveraged to tune solubility and to introduce a defined polar/ionizable element within a sequence, supporting structure-activity relationship studies and the preparation of reference compounds for binding or stability testing in chemical biology campaigns.
4. Pharmaceutical Intermediate Development
4-Carboxy-DL-tryptophan is also used as a defined intermediate precursor in synthetic programs that require indole-carboxylated tryptophan chemistry as an upstream motif. Process and development chemists employ it when downstream targets demand retention of the indole carboxylation pattern for subsequent functional group transformations, protecting-group strategies, or incorporation into larger heteroaromatic frameworks. The compound's amino acid functionality provides a convenient handle for controlled conversion into downstream intermediates, supporting reproducible feedstock preparation for custom synthesis and specialty chemical manufacturing where stereochemical mixture is acceptable at the intermediate stage.
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