L-allo-isoleucine is a naturally occurring amino acid belonging to the isoleucine family, featuring an α-amino and α-carboxylate-bearing backbone with a branched aliphatic side chain. The molecule contains a chiral center in the side-chain region consistent with the allo stereochemical designation, and it presents a hydrophobic, nonpolar side-chain functionality typical of amino acids used for peptide incorporation. L-allo-isoleucine is used as a defined building block for peptide synthesis and structure-activity studies, and it can serve as a stereochemically specific substrate or reference material in analytical method development and amino acid profiling.
CAT No: CP01202
CAS No:1509-34-8
Synonyms/Alias:L-allo-Isoleucine;L-Alloisoleucine;1509-34-8;(2S,3R)-2-amino-3-methylpentanoicacid;Allo-Isoleucine;Alloisoleucine;(3R)-LS-isoleucine;allo-L-Isoleucine;a-ile;Isoleucine,allo-;threo-L-Isoleucine;Isoleucine,threo-;L(+)-Alloisoleucine;L-Isoleucine,allo-;L-Isoleucine,threo-;threo-3-methyl-L-Norvaline;Norvaline,3-methyl-,threo-;CHEBI:43433;L-Norvaline,3-methyl-,threo-;L-Isoleucine,3-methyl-,threo-;alle;DL-Allo-isoleucine;EINECS216-142-3;(2S,3R)-2-amino-3-methylpentanoate;NSC206282
L-allo-Isoleucine is a naturally occurring L-amino acid stereoisomer featuring a chiral side chain derived from an isoleucine framework, with the α-amino and α-carboxyl functionalities positioned for standard amino acid coupling chemistry. The molecule contains a secondary stereocenter in the side chain (allo configuration) that can influence conformational preferences and stereochemical outcomes during derivatization, peptide bond formation, and downstream transformations. The free amino acid bears a primary amine and a carboxylic acid that can be selectively protected or converted into activated derivatives to support peptide synthesis, chiral building block preparation, and analytical reference standards. L-allo-isoleucine's reactivity profile aligns with amino acid intermediate usage, enabling formation of amide linkages, esterification for solubility control, and side-chain-compatible functional modifications relevant to peptide science and stereochemical studies.
1. Peptide Synthesis
L-allo-Isoleucine is applied in peptide synthesis as a chiral amino acid building block whose α-amino and α-carboxyl groups participate in standard coupling strategies to form amide bonds with controlled stereochemistry. The allo-configured side chain stereocenter can be used to probe how side-chain stereochemistry affects peptide conformations, backbone/side-chain packing, and coupling outcomes in iterative solid-phase or solution-phase assembly. Protection of the α-amino group and activation or protection of the carboxyl group can be selected to maintain the allo stereocenter while enabling orthogonal deprotection toward sequential chain elongation. Peptide analogs incorporating L-allo-isoleucine can serve as research-grade materials for studying stereodependent structure and for generating defined peptidomimetic scaffolds.
2. Unnatural Amino Acid Incorporation
L-allo-Isoleucine is suitable for chemical biology and synthetic biology workflows that require incorporation of stereochemically defined amino acid variants into peptide or protein-like constructs. The amino acid's L-configuration at the α-carbon and the allo stereochemistry at the side chain provide a defined chiral environment that can be exploited in unnatural amino acid incorporation studies, including the preparation of labeled or modified analogs for mechanistic investigations. Derivatization of the carboxyl group into an activated intermediate or conversion to a protected ester can support controlled coupling to amines, while N-protection strategies can preserve stereochemical integrity during multi-step synthesis. Incorporation into peptides and peptidomimetics enables downstream evaluation of stereochemical effects on molecular recognition, stability, and chemical reactivity patterns.
3. Side-Chain Functionalization
L-allo-Isoleucine is used in amino acid derivatization and side-chain functionalization routes where the branched aliphatic side chain provides a stereodefined platform for further chemical modification. The free carboxyl group can be protected or transformed into an ester or activated derivative to direct selective transformations, while α-amino protection can prevent undesired side reactions during functional group installation. Side-chain modification strategies can generate functional handles for subsequent conjugation, such as introducing groups that enable attachment to linkers, probes, or polymer backbones without perturbing the α-amino acid core. Resulting functionalized derivatives can be used as intermediates for constructing stereochemically defined conjugates, enabling controlled molecular assembly in applied chemical research and specialty chemical production.
4. Chiral Building Block Development
L-allo-Isoleucine is applied as a chiral amino acid intermediate for stereoselective synthesis of defined amino acid derivatives, including protected amino acid forms and chiral standards used in method development. The presence of two stereogenic elements (α-L configuration and allo side-chain stereocenter) supports the design of downstream intermediates where stereochemical fidelity is required during protection, activation, and coupling steps. Conversion to N-protected derivatives and carboxyl-activated species can facilitate peptide coupling chemistry while maintaining the allo configuration for reproducible stereochemical outcomes. Chiral derivative preparation from L-allo-isoleucine can also support analytical research, including reference material generation for stereochemical verification and impurity profiling in amino acid and peptide manufacturing contexts.
5. Analytical Research Standards
L-allo-Isoleucine is employed in analytical research as a stereochemically defined amino acid standard for chromatography, mass spectrometry method development, and stereochemical discrimination in complex mixtures. The compound's free amino acid functionality enables formation of derivatization products that can improve detectability and separation, while its allo stereochemistry provides a distinct retention and fragmentation behavior compared with other isoleucine stereoisomers. Carboxyl and amino groups can be selectively protected or converted into stable derivatives to generate consistent analytical signals across method platforms. Defined standards derived from L-allo-isoleucine can support quality control of peptide building blocks, verification of stereochemical composition in synthetic intermediates, and development of robust analytical workflows for amino acid and peptide chemistry.
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