H-L-Met-OH is a free amino acid derivative consisting of L-methionine (Met) with an N-terminal peptide-like formylated residue specified as H-L- and a carboxylic acid group (-COOH) at the C-terminus. The molecule contains an amino functional group (-NH2) and a thioether-containing side chain characteristic of methionine, with stereochemistry indicated by the "L" designation. It is used as a defined methionine-containing building block for peptide and amino acid derivative synthesis, as well as for solution-phase or solid-phase assembly and analytical method development involving methionine chemistry.
L-Methionine (H-L-Met-OH) is a proteinogenic amino acid in the L-configuration bearing a free α-amino group and a free α-carboxylic acid, with a side chain that terminates in a thioether (-CH2-CH2-S-CH3). The sulfur-containing side chain provides a distinct nucleophilicity and redox-reactive handle compared with non-sulfur amino acids, while the zwitterionic nature of the amino acid under aqueous conditions supports salt formation and controlled solubility. As an unprotected amino acid, L-Met-OH participates readily in peptide coupling chemistry after conversion to activated carboxyl derivatives and can be incorporated into peptide sequences or used as a chiral starting material for sulfur functionalization. The stereochemical integrity of the L-α-center makes it suitable for stereodefined peptide building and downstream derivatization where side-chain chemistry is the primary modification axis.
1. Peptide Synthesis
L-Methionine (H-L-Met-OH) is used in peptide building where the α-amino and α-carboxyl functionalities enable standard amino acid coupling after activation of the carboxyl group. The methionine side-chain thioether can be retained during peptide assembly or selectively transformed in later steps to generate thioether-to-sulfoxide/sulfone analogs or other sulfur-containing motifs. Incorporation of the L-configuration supports stereochemically defined amide bond formation and consistent backbone recognition in peptide analogs. Downstream peptide synthesis workflows frequently treat methionine as a residue for studying sequence effects, oxidation-sensitive behavior, and side-chain-dependent conformational or stability trends.
2. Amino Acid Derivatization
L-Methionine (H-L-Met-OH) serves as a direct substrate for amino acid derivatization strategies that target the sulfur-containing side chain while preserving the α-amino acid scaffold. The thioether can undergo controlled oxidation to sulfoxide or sulfone derivatives, enabling chemical biology probes and oxidation-state-responsive chemical handles. The free amine and carboxylic acid also support conversion to protected amino acid derivatives, esterification, or salt formation to tune reactivity and solubility for intermediate preparation. Resulting methionine-derived intermediates can feed into peptidomimetic construction, sulfur-functional material precursors, and fine chemical synthesis routes that require a chiral amino acid starting point.
3. Chemical Biology Labeling
L-Methionine (H-L-Met-OH) is applicable to chemical biology workflows that exploit sulfur-side-chain reactivity and amino acid recognition. The thioether side chain can be incorporated into peptide or small-molecule contexts, then selectively oxidized or functionalized to introduce polarity changes or reactive intermediates for subsequent conjugation chemistry. The presence of both α-amino and α-carboxyl groups enables formation of amide-linked probes, attachment to linkers, or preparation of conjugation-ready derivatives after appropriate activation. Methionine-containing constructs can be used to investigate oxidation-dependent processes, protein/peptide stability under controlled chemical environments, and side-chain-specific molecular recognition in biochemical research.
4. Protein Engineering Substrates
L-Methionine (H-L-Met-OH) is relevant to protein engineering and in vitro protein chemistry as a defined chiral amino acid component for constructing methionine-containing peptide segments and substrates. The L-α-amino acid stereochemistry supports predictable incorporation into peptide fragments that mimic protein regions, while the thioether side chain provides a chemically distinct locus for oxidation-state studies or side-chain substitution analogs. The unprotected α-functional groups can be transformed into activated building blocks for fragment assembly, enabling preparation of substrate libraries for enzyme assays or binding studies. Downstream use frequently includes generating methionine variants and sulfur-modified analogs to probe sequence-dependent behavior in protein-mimetic systems.
5. Pharmaceutical Intermediate Preparation
L-Methionine (H-L-Met-OH) can be employed as a chiral amino acid intermediate in pharmaceutical and specialty chemical manufacturing where sulfur-containing stereodefined building blocks are required. The free carboxylic acid and amino group support conversion into activated intermediates for amide bond formation, while the thioether side chain can be carried through as a stable functionality or transformed into oxidized sulfur analogs depending on the target scaffold. Process-oriented synthesis often uses methionine as a starting point for producing chiral intermediates that feed into heteroatom-containing fragments, linker units, or peptidomimetic motifs. Resulting derivatives can be integrated into downstream fine chemical synthesis and controlled manufacturing routes for complex molecule construction.
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