Fmoc-Lys(Ac)-OH is an Fmoc-protected lysine derivative in which the ε-amino side chain of lysine is acylated with an acetyl group, while the α-amino and α-carboxyl functionalities are present as part of the amino acid scaffold. The molecule contains the fluorenylmethoxycarbonyl (Fmoc) protecting group on the α-amino group and an acetyl (Ac) group on the ε-amino group, providing two distinct nitrogen protection elements that modulate chemoselectivity during stepwise assembly of peptide-related structures. In peptide synthesis workflows, it functions as a protected amino acid building block for introducing an acetylated lysine side chain, supporting controlled handling of the ε-amino functionality and enabling preparation of lysine-containing peptide intermediates for chemical biology and structural studies.
CAT No: CP26441
CAS No:159766-56-0
Synonyms/Alias:Fmoc-Lys(Ac)-OH;159766-56-0;Fmoc-N'-Acetyl-L-lysine;AC1Q1L6E;KSC005Q1N;SCHEMBL1738761;CTK9A5816;MolPort-016-581-063;ZINC2555141;(2S)-6-acetamido-2-(9H-fluoren-9-ylmethoxycarbonylamino)hexanoicAcid;CF-492;Nalpha-Fmoc-Nepsilon-acetyl-L-lysine;AKOS015895500;AJ-39705;AK-41444;AM017475;AN-31114;AB0020261;KB-301322;F1041;FT-0081967;FT-0601905;ST24047285;ST51052980;V1088
Fmoc-Lys(Ac)-OH is an Fmoc-protected lysine derivative in which the side-chain ε-amino group is acylated as an acetamide while the α-carboxylic acid remains free for peptide coupling. The molecule contains the stereogenic α-carbon of lysine, with the ε-nitrogen masked by an acetyl protecting group that modulates nucleophilicity and suppresses side reactions during standard amide bond formation. The fluorenylmethoxycarbonyl (Fmoc) group on the α-amino function is base-labile, enabling controlled N-deprotection under peptide-synthesis conditions, while the carboxylic acid supports activation to form amide linkages. Overall, the combination of orthogonal protection patterns and a defined lysine side chain makes Fmoc-Lys(Ac)-OH a chiral amino acid intermediate suited to constructing peptides and lysine-functionalized derivatives with predictable protecting-group behavior.
1. Peptide Synthesis
Fmoc-Lys(Ac)-OH is used in solid-phase peptide synthesis and related peptide building workflows where lysine incorporation requires orthogonal protection of the α-amino group and the ε-amino side chain. The Fmoc group enables stepwise N-terminal deprotection, while the ε-acetamide reduces competing ε-amine reactivity during coupling cycles. The free α-carboxylic acid participates in peptide coupling chemistry to generate amide bonds at the lysine position, supporting controlled chain elongation and minimizing side-chain crosslinking. The resulting lysine residue can be carried into downstream steps for selective ε-amide manipulation or conversion into other lysine-derived functionalities after appropriate deprotection or acyl exchange strategies. Fmoc-Lys(Ac)-OH therefore functions as a stereochemically defined, protected lysine building block for peptide construction and peptide analog preparation.
2. Protected Amino Acid Chemistry
Fmoc-Lys(Ac)-OH serves as a protected amino acid intermediate for derivatization chemistry that targets the lysine side chain while maintaining compatibility with peptide-grade protection schemes. The acetamide on the ε-nitrogen provides a stable, non-basic handle that can withstand many coupling and purification conditions, while the Fmoc carbamate can be removed selectively to expose the α-amine when needed for further transformations. The presence of a free α-carboxyl group supports conversion into activated esters or coupling-ready forms for intermediate synthesis beyond peptide assembly. Side-chain functionalization can be approached through acyl migration, selective deprotection, or controlled refunctionalization after the peptide or intermediate framework is established. This protection pattern aligns with amino acid derivatization and protected amino acid synthesis strategies used to prepare chiral intermediates for fine chemical manufacturing and research-grade building blocks.
3. Bioconjugation Chemistry
Fmoc-Lys(Ac)-OH is applicable to bioconjugation and chemical biology workflows where lysine-specific conjugation sites are required with controlled chemoselectivity. The lysine side chain, protected as an acetamide during synthesis, can be positioned within peptides or peptide-like scaffolds to control when and where the ε-nitrogen becomes available for subsequent conjugation chemistry. The Fmoc-protected α-amino functionality supports incorporation into defined sequences, enabling generation of conjugatable biomolecule constructs with predictable spacing and stereochemical consistency. Following assembly, the protected lysine residue can be transformed into a reactive amine or other lysine-derived linkage partner under conditions compatible with the conjugation target. Fmoc-Lys(Ac)-OH thus supports downstream biomolecule labeling, linker installation, and structured conjugate preparation grounded in lysine side-chain chemistry.
4. Peptidomimetics And SAR Studies
Fmoc-Lys(Ac)-OH is used in peptidomimetic and structure-activity relationship studies to incorporate a protected lysine motif into analog libraries with defined side-chain geometry and amide-forming capability. The α-carboxylic acid and Fmoc-protected α-amine enable construction of peptide-like backbones, while the ε-acetamide stabilizes the lysine side chain during analog synthesis and library generation. The stereogenic lysine center allows consistent chiral presentation of the side chain, which can influence molecular recognition in SAR workflows without requiring late-stage, less controllable functionalization. Subsequent transformations of the ε-amide can generate a range of lysine-derived functionalities, supporting systematic variation of charge, hydrogen-bonding, and linker chemistry across analog series. Fmoc-Lys(Ac)-OH therefore serves as a chiral amino acid building block for medicinal chemistry-oriented scaffold construction and SAR-driven analog development.
5. Pharmaceutical Manufacturing Intermediates
Fmoc-Lys(Ac)-OH is relevant to pharmaceutical manufacturing and process chemistry contexts where protected amino acid intermediates are assembled into peptide-based or peptide-derived materials under reproducible protection/deprotection logic. The Fmoc group provides a controllable N-protection strategy that can be removed on demand, while the ε-acetamide reduces undesired side reactions during coupling and intermediate isolation steps. The free carboxylic acid supports standardized activation and coupling operations typical of peptide intermediate preparation, enabling scalable synthesis of defined lysine-containing segments. The resulting protected lysine unit can be carried through downstream steps to generate intermediates for larger drug substance fragments, analytical standards, or formulation-relevant peptide components. Fmoc-Lys(Ac)-OH aligns with industrial amino acid derivative handling where orthogonal protection patterns and chiral integrity are important for robust manufacturing routes.
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