Fmoc-L-Lys(Biotin)-OH

Fmoc-L-Lys(Biotin)-OH is an Fmoc-protected lysine derivative bearing a biotinylated side chain, combining a stereodefined \alpha-amino acid backbone with a protected \alpha-amino group for orthogonal peptide chemistry. The molecule features a free carboxylic acid for C-terminal coupling, an Fmoc carbamate on the \alpha-amino nitrogen for base-labile deprotection, and a lysine side chain functionalized with biotin, which contains a ureido ring and a fused hydrophobic bicyclic framework capable of strong biomolecular recognition. The biotin substituent introduces additional amide and ureido functionalities that can participate in hydrogen bonding and can be used as a handle for affinity-based conjugation strategies. The overall reactivity profile is governed by the protected amine, the carboxylic acid, and the biotin functional group set, making the compound a chiral, peptide-compatible intermediate for constructing biotinylated peptides and bioconjugation-ready building blocks.

1. Peptide Synthesis

Fmoc-L-Lys(Biotin)-OH is used in peptide synthesis workflows where biotin-bearing lysine residues are required for affinity-tagged sequences. The Fmoc-protected \alpha-amino group supports standard solid-phase peptide coupling after deprotection, while the free C-terminal carboxylic acid enables amide bond formation to neighboring residues. The lysine side chain provides a spatially accessible biotin motif that can remain intact under typical Fmoc deprotection conditions, supporting downstream binding assays and capture formats. Biotinylated peptides prepared from this building block can be applied to binding studies, pull-down compatible probes, and peptide-based molecular recognition experiments, linking amino acid chemistry directly to conjugation-ready peptide architecture.

2. Bioconjugation Chemistry

Fmoc-L-Lys(Biotin)-OH serves as a defined bioconjugation intermediate for constructing affinity-reactive biomolecules via biotin recognition chemistry. The compound's stereochemistry and lysine scaffold position the biotin moiety as a pendant functional group, while the Fmoc group provides a controlled handle for incorporation into peptide chains before conjugation. The ureido and amide-rich biotin framework can participate in high-specificity binding interactions with streptavidin or avidin, enabling stable labeling of peptide constructs and biomolecule-derived materials. Downstream derivatives can be generated by incorporating the biotin-bearing residue into peptides, linkers, or protein-interfacing domains, after which affinity capture and detection steps can be performed using the biotin functionality.

3. Side-Chain Functionalization

Fmoc-L-Lys(Biotin)-OH is suitable for side-chain functionalization strategies that require a lysine-based attachment point carrying a biologically recognizable moiety. The protected amino acid derivative format allows controlled incorporation into peptide backbones while preserving the biotin side-chain chemistry as a functional group for later use. The biotin substituent introduces additional heteroatoms and hydrogen-bonding capacity, which can influence solubility and molecular conformation in peptide contexts and can be exploited when designing probes with defined recognition elements. Synthetic routes that rely on orthogonal protection and selective deprotection can employ this building block to generate biotinylated analogs for chemical biology research, molecular scaffolding, and affinity-based reagent preparation.

4. Protein Engineering

Fmoc-L-Lys(Biotin)-OH can be applied in protein engineering and protein labeling design where site-specific biotin installation is needed on peptide segments used to assemble larger constructs. The lysine residue provides a canonical amino acid side chain for peptide incorporation, while the biotin moiety functions as a recognition tag that can be placed at defined sequence positions through peptide synthesis. The Fmoc-protected \alpha-amino group supports controlled residue placement during assembly of biotinylated peptides that may serve as domains, linkers, or attachment modules for engineered proteins. Resulting biotinylated peptide components can be used to guide affinity purification, mapping of interaction interfaces, and preparation of protein conjugates that depend on stable biotin-avidin type binding.

5. Pharmaceutical Manufacturing

Fmoc-L-L-Lys(Biotin)-OH is relevant to pharmaceutical manufacturing contexts that require reproducible preparation of biotin-containing peptide intermediates used for analytical, process, or formulation support. The presence of an Fmoc-protected amine and a free carboxylic acid makes the compound compatible with peptide coupling steps that generate defined, sequence-controlled intermediates, including biotinylated reference materials. The biotin side chain offers a standardized affinity handle that can be used for in-process capture, analytical enrichment, and characterization of peptide-derived components. Industrially, the compound can function as a chiral, protected amino acid input for fine chemical synthesis of biotin-tagged peptides, supporting downstream material generation where controlled functional group placement is required.

6. Analytical Research

Fmoc-L-L-Lys(Biotin)-OH is used in analytical research to prepare biotinylated peptide standards and affinity reagents for detection and characterization workflows. The Fmoc-controlled peptide building block format enables incorporation of the biotin motif into defined sequences, supporting consistent signal generation and reproducible binding behavior in assay formats. The biotin functional group provides a robust recognition element for enrichment, immobilization, and assay readouts, while the lysine backbone supports predictable peptide handling and conjugation geometry. Analytical applications can include calibration or reference peptide preparation, affinity-based sample enrichment, and development of peptide probes for studying molecular interactions where biotin capture is part of the measurement strategy.

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