L-Theanine is an L-configured non-proteinogenic amino acid featuring an ethylamide-linked 5-(ethylcarbamoyl)-pyrrolidin-2-yl group, placing a side-chain moiety on the alpha-amino acid backbone. The molecule contains a free alpha-amino group and a free carboxyl functional group alongside a secondary amide within the side chain, which can participate in hydrogen bonding and modulate polarity relative to standard aliphatic amino acids. L-Theanine is used as a defined amino acid building block and reference compound in peptide chemistry, chemical biology, and analytical method development where its amide-bearing, non-proteinogenic structure supports studies of structure-property relationships and incorporation into synthetic peptide analogues.
CAT No: CP09103
CAS No:3081-61-6
Synonyms/Alias:L-Theanine;Theanine;3081-61-6;Theanin;(S)-2-Amino-5-(ethylamino)-5-oxopentanoicacid;N-gamma-Ethyl-L-glutamine;N-Ethyl-L-glutamine;Suntheanine;L-gamma-Glutamylethylamide;N5-Ethyl-L-glutamine;N(5)-ethyl-L-glutamine;(2S)-2-amino-5-(ethylamino)-5-oxopentanoicacid;UNII-8021PR16QO;CCRIS7326;CHEBI:17394;DATAGRPVKZEWHA-YFKPBYRVSA-N;EINECS221-379-0;NSC21308;(+)-Theanine;PubChem13022;L-Glutamine,N-ethyl-;Spectrum2_001693;Spectrum3_001137;Spectrum4_001984;Spectrum5_000897
L-Theanine is a naturally occurring L-amino acid derivative featuring a γ-glutamyl backbone linked to an ethylamide-bearing side chain, with two key polar functionalities: a carboxylic acid and a primary amide. The stereochemistry is defined at the α-carbon of the glutamate-derived moiety (L-configuration), which governs recognition in biochemical assays and influences coupling behavior during amino acid esterification and amidation. The molecule's side-chain amide and carboxyl group enable strong hydrogen-bonding interactions and allow conversion into protected or activated derivatives for peptide coupling chemistry. L-Theanine also serves as a chemically stable chiral nitrogen-containing intermediate that can be transformed into N-protected analogs or functionalized derivatives for downstream synthetic and analytical workflows.
1. Peptide Synthesis
L-Theanine finds use in peptide building block preparation and peptide coupling chemistry where its amino acid framework can be converted into activated carboxyl derivatives for amide bond formation. The presence of both a carboxyl group and a side-chain amide enables controlled C-terminal or side-chain functionalization strategies, including esterification for temporary protection and subsequent deprotection to regenerate coupling-ready acids. L-Theanine-derived activated intermediates can be incorporated into peptide-like scaffolds to probe how the γ-glutamyl connectivity and ethylamide side chain affect backbone conformation and amide hydrogen-bonding patterns. Downstream peptide analog construction often relies on these structural features to generate theorelevant intermediates for chemical biology and peptidomimetic studies.
2. Chemical Biology Research
L-Theanine is applied in chemical biology research as a chiral amino acid probe for studying amino acid transport, receptor binding, and enzyme-mediated transformations where side-chain amide polarity and the L-stereocenter are central to molecular recognition. The glutamate-derived skeleton and ethylamide functionality can participate in hydrogen-bond networks that influence assay readouts in binding and competition formats. L-Theanine can also be derivatized into labeled or immobilizable forms through selective modification of the carboxyl group (e.g., ester/amide formation) while preserving the side-chain amide for consistent recognition. These properties support its role as a biochemical research intermediate for mechanistic studies and molecular interaction mapping in amino acid chemistry.
3. Analytical Standards Development
L-Theanine serves as an analytical reference material for amino acid profiling and method development in chromatography and mass spectrometry workflows that require stereochemically defined standards. The molecule's defined L-configuration and characteristic amide/carboxyl functionality produce reproducible retention and fragmentation patterns that can be used to validate derivatization strategies and quantitation methods. L-Theanine can be converted into isotopically labeled or derivatized forms to improve detectability while maintaining the core structural motif used for identification. Analytical research applications therefore leverage its structural features to support robust identification of theanine-containing matrices and amino acid derivative mixtures.
4. Bioconjugation Chemistry
L-Theanine can be employed in bioconjugation chemistry as a chiral amino acid handle for constructing amide-linked conjugates to proteins, peptides, or polymer backbones. The carboxylic acid enables formation of stable amide or ester linkages to introduce theanine-derived motifs into larger biomolecular assemblies, while the side-chain amide can remain intact to preserve the polar recognition elements. Protection-group strategies such as temporary activation of the acid and selective N-protection of the amide can help control chemoselectivity during conjugation and subsequent deprotection. Downstream biomolecule modification benefits from the compound's ability to act as a defined nitrogen-rich linker component in applied biochemical research and materials-oriented conjugate synthesis.
5. Pharmaceutical Intermediate Preparation
L-Theanine is suitable for pharmaceutical intermediate preparation where its chiral amino acid structure can be transformed into protected amino acid derivatives and activated intermediates for medicinal chemistry synthesis. The carboxyl group can be converted into acid chlorides, activated esters, or protected forms that participate in controlled peptide coupling or scaffold assembly, while the side-chain amide provides a polar functional handle that can be retained or further modified. Selective protection of the α-amino functionality (when present as a protected derivative) and controlled deprotection sequences enable incorporation into larger heteroamide-containing structures common in drug discovery chemistry. Process chemistry routes may therefore use L-theanine as a defined stereochemical precursor for generating amino acid-derived fragments and fine chemical intermediates.
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