Fmoc-D-Lys(Biotin)-OH

Fmoc-D-Lys(Biotin)-OH is an Fmoc-protected D-lysine derivative bearing a biotinylated side chain at the ε-amino position, forming a chiral, amino-acid-based peptide building block with a protected α-amino group and a free carboxylic acid for coupling. The molecule combines an aromatic fluorenylmethoxycarbonyl (Fmoc) group for orthogonal amine protection, a stereogenic center at the lysine α-carbon (D-configuration), and a biotin moiety that introduces a fused heterocycle-like recognition motif with multiple heteroatoms for hydrogen-bonding and binding interactions. The ε-amino functionality is converted into a biotin-conjugated amide/urea-like linkage pattern depending on the side-chain attachment chemistry, while the presence of the carboxylic acid supports standard peptide coupling and downstream functionalization. The overall reactivity profile is dominated by Fmoc deprotection under base and carboxyl activation during peptide bond formation, making it a practical intermediate for constructing biotin-displaying peptides and conjugates.

1. Peptide Synthesis

Fmoc-D-Lys(Biotin)-OH supports solid-phase peptide synthesis and fragment condensation workflows where a biotin-presenting lysine residue is required at a defined position within a peptide sequence. The protected α-amino group provided by Fmoc enables controlled N-terminal assembly, while the free C-terminal carboxylic acid participates in peptide coupling chemistry to form amide linkages with activated carboxyl partners. The D-lysine stereochemistry can be incorporated to probe stereochemical effects on folding, protease recognition, and binding behavior in peptide analogs. The biotin side-chain remains available for post-synthetic capture or affinity-based detection, enabling downstream generation of biotinylated peptide libraries and sequence-defined conjugates for biochemical research.

2. Bioconjugation Chemistry

Fmoc-D-Lys(Biotin)-OH is suitable for chemical biology and bioconjugation strategies that require site-specific biotin display for affinity enrichment, pull-down assays, and immobilization onto streptavidin or avidin surfaces. The lysine scaffold provides a stable linkage point for attaching the biotin motif to a peptide or protein fragment, while the Fmoc group allows orthogonal handling during synthesis and subsequent deprotection to expose the amine for further coupling steps when needed. The biotin-bearing side chain introduces strong noncovalent recognition functionality that can be leveraged in workflows such as affinity capture of peptide conjugates, imaging probe targeting, or surface immobilization of biomolecular constructs. The resulting biotinylated products can serve as intermediates for generating higher-order conjugates, including multivalent binders and modular assay reagents.

3. Protein Engineering

Fmoc-D-Lys(Biotin)-OH can be applied in protein engineering contexts where defined biotin labeling is introduced through peptide-mediated assembly or through incorporation into peptide segments used for protein semisynthesis. The protected amino acid form enables sequence-controlled placement, and the D-configuration at the lysine α-carbon can be used to tune local conformation, proteolytic stability, and interaction patterns relative to L-lysine analogs. The biotinylated ε-side chain functions as a recognition handle that can be carried into larger biomolecular architectures, including engineered domains, binding scaffolds, and affinity-tagged constructs. The compound's amino-acid chemistry compatibility supports downstream conversion into peptide fragments that can be ligated or assembled into protein constructs, aligning with industrially relevant workflows for producing functional biomolecule building blocks.

4. SAR Studies

Fmoc-D-Lys(Biotin)-OH enables structure-activity relationship studies by allowing systematic variation of biotin-bearing lysine placement, stereochemistry, and linker context within peptide or peptidomimetic scaffolds. The Fmoc-protected α-amino group and free carboxylic acid support consistent peptide coupling, facilitating parallel synthesis of analog series with controlled sequence position and side-chain identity. The biotin moiety can act as an affinity tag or as a recognition element that supports comparative assays, while the D-lysine stereocenter provides an additional structural parameter for evaluating how stereochemistry influences binding, stability, and assay readouts. The resulting peptide analogs can be used as chemically defined tools for correlating molecular structure with functional outcomes in biochemical screening and mechanistic studies.

5. Pharmaceutical Manufacturing

Fmoc-D-Lys(Biotin)-OH is applicable to pharmaceutical manufacturing and specialty chemical production processes that require reproducible preparation of biotinylated peptide intermediates for analytical, process, or formulation-related purposes. The amino acid ester-free carboxylic acid and orthogonally removable Fmoc protection support robust peptide coupling and deprotection logic within controlled manufacturing-style synthesis planning. The biotin side chain provides a stable affinity handle that can be used to generate reference materials, process monitoring reagents, or immobilized standards for method development and validation workflows. The compound therefore functions as a chiral, protected amino acid intermediate that integrates peptide synthesis compatibility with downstream affinity-based handling in applied industrial chemistry settings.

6. Analytical Research

Fmoc-D-Lys(Biotin)-OH can be employed in analytical research to produce biotin-displaying peptide standards and calibration materials for affinity-based detection platforms. The Fmoc-protected amino acid format supports consistent synthesis of defined peptide sequences, while the D-lysine stereochemistry can be selected to match specific assay designs that discriminate stereochemical variants. The biotin side chain enables capture on streptavidin/avidin-coated surfaces, supporting workflows such as surface immobilization for biosensor measurements, enrichment prior to LC-MS analysis, and normalization of signal across experimental runs. The resulting biotinylated peptides serve as chemically characterized intermediates that connect amino acid derivatization chemistry to measurable analytical outputs.

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