Ac-D-Met-OH is an acetylated, D-configured methionine derivative featuring a thioether-containing side chain and a free carboxylic acid, with the amino group capped as an N-acetyl (Ac) amide. The molecule therefore bears an amide nitrogen rather than a free α-amino functionality, while maintaining the α-carboxyl group as the terminal acid for salt formation or coupling chemistry, and it retains the stereochemical identity implied by the D prefix. In synthesis and chemical biology workflows, Ac-D-Met-OH is used as a protected or derivatized amino acid building block and as a substrate analogue for studying peptide bond formation, amino acid recognition patterns, or labeling and analytical methods that distinguish acetylated versus free amino termini.
Ac-D-Met-OH is an N-acetylated D-methionine amino acid derivative supplied as a free carboxylic acid, featuring the D stereochemistry at the alpha carbon and a methionine side chain with a thioether functionality. The N-acetyl group blocks the amino terminus, making the compound a defined, non-proteinogenic building block for controlled peptide and peptidomimetic assembly, as well as a stereochemically specified reference material in analytical workflows where D-Met-containing structures are relevant. In practice, Ac-D-Met-OH is handled as a stable, well-defined intermediate that supports downstream conversion into N-acetylated peptide segments or standards without introducing an unprotected amino group.
1. N-Acetyl Peptide Building Block
Ac-D-Met-OH is used by peptide chemists to introduce an N-acetylated D-methionine residue into short peptides, peptidomimetics, and research-grade analogs where the blocked N-terminus is required from the outset. The N-acetylation state helps ensure that subsequent coupling steps proceed from the carboxyl functionality without competing amino reactivity, enabling consistent segment design for custom peptide synthesis and library construction. Its D configuration allows stereochemical control in studies that compare L- versus D-containing sequences, including stability and structure-property investigations in chemical biology and protein engineering workflows.
2. Chiral Reference And Analytical Standard
Ac-D-Met-OH is commonly selected as a stereochemically defined reference material for analytical method development and validation involving D-methionine-containing motifs, such as targeted LC-MS workflows for peptide fragments, derivatized amino acid standards, or impurity/identity checks in peptide intermediate qualification. The N-acetyl group provides a distinct mass and derivatization behavior compared with free D-Met, which can improve specificity when monitoring N-terminally capped species. Researchers in analytical chemistry and peptide manufacturing development use such standards to calibrate quantitation, confirm identity, and support method transfer across instrumentation platforms.
3. Peptidomimetic And SAR Intermediates
Ac-D-Met-OH serves as a practical intermediate for preparing N-acetylated methionine-containing fragments used in medicinal chemistry and peptidomimetic development. The thioether side chain of methionine supports the construction of sulfur-containing analogs and related structural motifs, while the N-acetyl cap provides a defined terminal functionality that can be carried through to larger conjugates or fragment-based assemblies. Teams developing structure-activity relationship (SAR) series often rely on such stereochemically specified, terminally protected amino acid derivatives to keep sequence endpoints consistent across analog synthesis campaigns.
4. Thioether-Containing Fragment Synthesis
Ac-D-Met-OH is applied when a sulfur-containing (thioether) side-chain fragment is needed with a blocked alpha-amino terminus for controlled downstream functionalization or incorporation into larger chemical entities. In chemical biology and materials-oriented research, defined thioether-bearing amino acid derivatives can be used to generate peptide-based linkers or segment precursors where the N-acetyl group prevents unwanted amine participation during coupling or assembly steps. This makes Ac-D-Met-OH a useful reagent for building structured fragments that later undergo conversion into more complex architectures under standardized synthetic conditions.
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