H-D-His(1-Me)-OH

H-D-His(1-Me)-OH is a deuterated, N-acetyl-free histidine derivative presented as the free amino acid methylated at the N1 position (1-Me) and bearing deuterium at the alpha position (H-D). The molecule retains the histidine side-chain imidazole ring, enabling acid-base behavior and coordination chemistry, while the N1-methyl substitution modulates imidazole protonation and can influence peptide coupling and N-alkylation selectivity. The free carboxylic acid and primary amino functionality support standard amino acid chemistry, including esterification, salt formation, and activation for amide bond formation. Deuterium labeling and the stereodefined chiral amino acid framework make the compound suitable as a tracer and mechanistic probe in amino acid and peptide transformations, as well as a chemically defined intermediate for downstream labeled derivatives.

1. Isotope-Labeled Metabolism Studies

H-D-His(1-Me)-OH is applied in chemical biology and analytical research as a deuterated histidine analog to probe histidine handling in peptide and amino acid reaction networks. The imidazole side chain and the N1-methyl substitution provide a defined microenvironment for proton transfer and metal binding, while the deuterium at the alpha position enables kinetic isotope effects and mass-shift tracking by LC-MS. The free amino acid form can be converted into labeled esters, activated derivatives, or incorporation-ready building blocks for studying labeled transfer into amide-linked products. Downstream use often includes preparing labeled peptides or monitoring labeled intermediates to support mechanistic interpretation of amino acid derivatization and degradation pathways in biochemical assays.

2. Peptide Coupling Building Block

H-D-His(1-Me)-OH is suitable for peptide synthesis workflows where a histidine-based residue with N1-methyl modulation is required. The amino acid backbone contains a carboxylic acid and an amino group that can be activated for amide bond formation, while the imidazole side chain can participate in selective protection strategies or remain compatible depending on the coupling chemistry employed. The N1-methyl group can affect imidazole nucleophilicity and protonation state during coupling, which may influence side reactions and the choice of protecting-group strategy for the imidazole nitrogen(s). Deuterium labeling further supports the construction of structurally defined peptide standards and labeled peptide libraries used to validate coupling efficiency, fragmentation patterns, and stereochemical integrity in peptide analysis.

3. Chiral Amino Acid Intermediate

H-D-His(1-Me)-OH functions as a chiral amino acid intermediate for synthetic organic chemistry routes that require a deuterated, N1-methylated histidine scaffold. The stereodefined alpha-deuterium center enables stereochemical tracking through downstream transformations, including conversion to protected amino acid derivatives, peptide-ready activated forms, or side-chain functionalization intermediates. The imidazole ring provides a functional handle for coordination-controlled chemistry and for selective derivatization strategies that preserve the labeled backbone. Downstream synthetic utility includes preparing labeled building blocks for peptidomimetic construction, generating reference materials for method development, and enabling route-specific isotope tracing in process chemistry intermediate preparation.

4. Bioconjugation And Labeling

H-D-His(1-Me)-OH can be utilized in biomolecule labeling contexts where histidine-like coordination and defined labeling chemistry are required. The imidazole side chain supports interactions with metal-containing tags and can participate in controlled conjugation schemes after conversion to activated carboxyl derivatives or protected forms compatible with bioconjugation conditions. The N1-methyl substitution provides a predictable electronic profile for imidazole protonation behavior, which can help stabilize conjugation intermediates and improve reproducibility of labeling reactions. Deuterium incorporation enables sensitive mass-based detection of labeled conjugates, supporting analytical confirmation of conjugation extent and aiding studies of biomolecular recognition involving histidine-containing motifs.

5. Analytical Research Standards

H-D-His(1-Me)-OH serves as a chemically defined analytical standard for amino acid and peptide quantification, method development, and isotope-resolved mass spectrometric studies. The deuterium label and the N1-methyl histidine structure create a distinct mass signature that supports unambiguous identification of labeled analytes in complex matrices. The free amino acid functionality enables straightforward derivatization to match common analytical formats, including esterification or conversion to chromatographically compatible derivatives. Downstream relevance includes calibrating isotope dilution workflows, validating peptide hydrolysis or digestion readouts, and supporting structure-confirming analysis for histidine-containing peptide building blocks and derivatized amino acid intermediates.

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