H-His(3-Me)-OH is a free, proteinogenic amino acid derivative based on the histidine scaffold, bearing a side chain substituted with a methyl group at the 3-position of the imidazole ring. The molecule contains an amino group and a carboxylic acid functional group, with the substituted imidazole providing a basic, heteroaromatic side-chain that can participate in acid-base equilibria and metal coordination in solution. As a non-protected amino acid analogue, it is used in peptide and amino acid chemistry workflows such as structure-activity studies, synthesis of modified histidine-containing peptides, and analytical method development where controlled variation of the histidine side-chain electronics is required.
H-His(3-Me)-OH is an amino acid derivative corresponding to L-histidine bearing a methyl substituent at the 3-position of the imidazole ring, retaining the amino acid backbone with a free primary amine and a free carboxylic acid. The imidazole N-containing heteroaromatic side chain is sterically and electronically tuned by the ring methyl group, which can modulate protonation behavior and metal-binding coordination relative to unsubstituted histidine. The molecule's zwitterionic character under aqueous conditions and the presence of both carboxyl and amine functional groups make it a reactive intermediate for protected amino acid synthesis and for downstream peptide coupling chemistry. Stereochemical assignment at the alpha-carbon supports incorporation into stereodefined peptide sequences and chiral structure-function studies where histidine side-chain identity is required.
1. Peptide Synthesis
H-His(3-Me)-OH serves as a histidine analog for peptide building and sequence design in solid-phase or solution-phase coupling workflows. The free alpha-amino and carboxylic acid groups enable standard peptide coupling strategies after appropriate temporary protection, while the 3-methyl imidazole side chain participates in side-chain-specific recognition and can be used to probe how imidazole substitution affects amide bond formation and subsequent peptide properties. The ring methyl group can influence imidazole protonation during synthesis and purification, supporting controlled handling of acid-base behavior in peptide intermediates. Peptide building block preparation from H-His(3-Me)-OH also supports the generation of histidine-substituted analogs for mechanistic studies and peptide material development.
2. Chemical Biology Probes
H-His(3-Me)-OH is suitable for chemical biology research where histidine-like metal coordination, pH-dependent behavior, or side-chain microenvironment effects are investigated using controlled amino acid substitutions. The imidazole heterocycle with a defined 3-methyl substituent provides a handle for designing biomolecule probes that mimic histidine binding motifs while altering steric and electronic features. The amino acid's free functional groups allow conversion into activated derivatives for incorporation into peptides, linkers, or affinity tags, enabling targeted studies of protein-ligand interactions and binding-site chemistry. Downstream functionalization can yield conjugatable constructs for mapping interaction networks and for generating analog libraries in biochemical research.
3. Protein Engineering Studies
H-His(3-Me)-OH can be applied to protein engineering and in vitro expression systems requiring stereodefined chiral amino acid building blocks for site-specific incorporation of modified histidine residues. The alpha-amino acid functionality supports incorporation into peptide chains, while the 3-methyl imidazole side chain can be used to tune local charge distribution, hydrogen-bonding patterns, and coordination geometry at engineered positions. The compound's defined stereochemistry at the backbone carbon helps maintain compatibility with translation or ligation chemistries that discriminate stereochemical configuration. Resulting protein variants or protein fragments can be used for structure-function investigations of metal-binding proteins, enzyme active sites, and conformational effects driven by histidine substitution.
4. Side-Chain Functionalization
H-His(3-Me)-OH provides a starting point for side-chain functionalization strategies that target the imidazole environment while preserving the amino acid backbone for further synthetic elaboration. The 3-methyl imidazole can be leveraged to control reactivity patterns in derivatization steps, including formation of conjugation-ready intermediates or incorporation into peptidomimetic scaffolds where imidazole electronics are intentionally modified. The free carboxylic acid and amine enable preparation of protected amino acid derivatives and activated ester or coupling partners that maintain stereochemical integrity through multi-step sequences. Functionalized downstream products can serve as intermediates for labeled probes, affinity reagents, or scaffold diversification in synthetic organic chemistry and biochemical assay development.
5. Process Chemistry Intermediate
H-His(3-Me)-OH is useful as a chiral amino acid intermediate for fine chemical synthesis where histidine-substituted motifs are required in controlled manufacturing routes. The compound's stable amino acid framework, with both amine and carboxylic acid present, supports conversion into N-protected and/or C-activated forms that are compatible with peptide coupling chemistry and with industrial-scale intermediate preparation. The imidazole ring methyl substituent provides a defined structural element that can be carried through manufacturing sequences to yield consistent substituted peptide fragments or peptidomimetic intermediates. Downstream formation of protected amino acid derivatives and coupling-ready intermediates from H-His(3-Me)-OH supports reproducible production of stereodefined building blocks for specialty chemical production and applied peptide manufacturing workflows.
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