Fmoc-D-Lys-OH

Fmoc-D-Lys-OH is an Fmoc-protected D-lysine amino acid bearing a free carboxylic acid and an unprotected ε-amino side chain in the D-configuration at the α-carbon. The fluorenylmethoxycarbonyl (Fmoc) group masks the α-amino functionality, enabling controlled peptide coupling after base-mediated Fmoc removal. The molecule combines a stereochemically defined chiral center with a primary amine side chain that can participate in orthogonal protection, nucleophilic acylation, and side-chain derivatization. The presence of both a carboxylic acid and a protected α-amine makes it a practical chiral building block for peptide synthesis, while the ε-amine supports downstream functionalization routes for structure-defined analogs and industrial intermediate preparation.

1. Peptide Synthesis

Fmoc-D-Lys-OH is used in solid-phase peptide synthesis and solution-phase peptide coupling workflows where a D-lysine residue is required for conformational control or protease resistance. The Fmoc-protected α-amino group supports standard peptide bond formation, while the free ε-amino side chain enables side-chain functionalization or orthogonal protection prior to chain assembly. The D-stereochemistry at the lysine α-carbon provides a defined chiral center that can be incorporated into peptide sequences to tune backbone stereochemistry and recognition. The resulting peptide products can be advanced into fragment libraries, mechanistic studies, and peptidomimetic scaffolds that retain lysine-like charge features through side-chain chemistry.

2. Side-Chain Functionalization

Fmoc-D-Lys-OH is applied in amino acid derivatization and chemical biology labeling strategies that require a lysine handle for selective conjugation. The unprotected ε-amine can undergo acylation, reductive amination, sulfonylation, or coupling to electrophiles, while the Fmoc group maintains α-amino protection during side-chain modification. Orthogonal protection of the ε-amine can be designed to preserve compatibility with peptide coupling cycles, enabling sequential installation of functional groups such as linkers, affinity tags, or reactive moieties. Downstream derivatives can serve as intermediates for bioconjugation-ready amino acid building blocks and for constructing charge-defined molecular probes.

3. Protected Amino Acids

Fmoc-D-Lys-OH is suitable as a chiral protected amino acid intermediate for manufacturing routes that require reliable orthogonal protection logic in peptide-grade synthesis. The Fmoc group provides a base-labile protecting group for the α-amino functionality, supporting controlled deprotection steps during automated synthesis or stepwise manufacturing. The free carboxylic acid participates in activation chemistry for amide formation, while the ε-amino side chain can be protected as needed to prevent undesired crosslinking or branching during coupling. The stereodefined D-lysine scaffold can be carried through process chemistry as a consistent input to generate D-lysine-containing peptide building blocks and downstream fine chemical intermediates.

4. Bioconjugation Chemistry

Fmoc-D-Lys-OH is used to prepare lysine-based conjugation intermediates for biomolecule modification and chemical biology reagent development. The ε-amino group provides a nucleophilic site for attaching fluorophores, biotin analogs, affinity ligands, or polymerizable handles, while the Fmoc-protected α-amine helps maintain chemoselectivity during initial functionalization steps. The D-configuration can be leveraged to modulate stability and binding behavior of resulting conjugates in assays that depend on stereochemical fidelity. The compound's amino acid framework supports downstream conversion into peptide conjugates, labeled probes, or peptidomimetic constructs compatible with analytical characterization and subsequent coupling to larger biomolecular targets.

5. Peptidomimetics And SAR Studies

Fmoc-D-Lys-OH is applied in peptidomimetic construction and structure-activity relationship studies where D-lysine incorporation is used to probe stereochemical effects on binding and stability. The combination of a protected α-amino group and a modifiable ε-amino side chain enables systematic variation of charge presentation, linker length, and functional group identity across analog series. The chiral center at the α-carbon supports reproducible stereochemical placement within peptide-like scaffolds, while side-chain derivatization supports tuning of solubility, electrostatics, and interaction motifs. The resulting D-lysine-containing analogs can be progressed as SAR materials and as reference standards for analytical research workflows that require stereochemically defined amino acid derivatives.

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