Boc-L-Lys(Ns)-OH is a protected, naturally occurring amino acid derivative of L-lysine bearing an Nε-(Ns) substituent and an N-terminal Boc (tert-butoxycarbonyl) protecting group. The molecule contains a free carboxylic acid and a Boc-protected α-amino group, while the lysine side chain is characterized by an Ns (nosyl) group on the ε-nitrogen that modulates nucleophilicity and provides chemoselective control during peptide coupling. Boc-L-Lys(Ns)-OH is used as a stepwise building block in peptide synthesis and related amino acid derivatization workflows where orthogonal protection of the lysine side-chain amine supports sequential assembly and downstream functionalization.
CAT No: CP25290
CAS No:1301706-36-4
Synonyms/Alias:Boc-Lys(Ns);N-alpha-Boc-N-epsilon-nosyl-L-lysine;N-alpha-Boc-N-epsilon-(2-nitrobenzenesulfonyl)-L-lysine
Chemical Name:N-alpha-t-Butyloxycarbonyl-N-epsilon-(2-nitrobenzenesulfonyl)-L-lysine, N-alpha-Boc-N-epsilon-nosyl-L-lysine
Boc-L-Lys(Ns)-OH is a protected lysine building block bearing an Nα-Boc group and a side-chain Ns (neopentylsulfonyl) protecting group, providing orthogonal protection for controlled peptide assembly. The lysine ε-amino functionality is masked as a sulfonamide, while the backbone nitrogen is protected for compatibility with standard protected-amino-acid coupling workflows. This reagent is commonly selected when lysine side-chain deprotection and subsequent functionalization are planned as a distinct downstream step.
1. Solid-Phase Peptide Synthesis
Boc-L-Lys(Ns)-OH is used in solid-phase peptide synthesis to incorporate a lysine residue whose ε-amino group is protected as the Ns sulfonamide, minimizing side reactions during chain elongation. Peptide synthesis groups typically choose this form when they want to defer lysine side-chain activation or modification until later in the synthesis sequence, while maintaining a stable, protected side chain through repetitive coupling and deprotection cycles. The Boc-protected α-amino group supports routine peptide assembly strategies, enabling reliable incorporation of lysine-containing segments in research-grade peptide libraries and custom peptide manufacturing.
2. Lysine Side-Chain Orthogonal Functionalization
Boc-L-Lys(Ns)-OH is frequently selected for workflows that require lysine ε-side-chain chemistry after the peptide backbone is assembled, such as converting the lysine side chain into an amine-reactive intermediate for subsequent derivatization. Chemical biology and peptide engineering teams use this protected lysine to manage chemoselectivity, keeping the ε-amino group masked during earlier synthetic steps and then unmasking it when installing tags, linkers, or other functional motifs on the peptide. This approach is particularly useful for producing site-defined lysine-modified peptides where controlling the timing of side-chain deprotection improves reproducibility across parallel syntheses.
3. Peptide Linker and Conjugate Precursor
Boc-L-Lys(Ns)-OH serves as a practical precursor for generating lysine-containing peptides that act as conjugation handles in bioconjugation development. Researchers preparing peptide conjugates for affinity reagents, labeling constructs, or immobilization strategies rely on Ns-protected lysine to suppress premature ε-amino reactivity during peptide synthesis, then enable downstream conversion to an amine-bearing form suitable for coupling to activated electrophiles. In these workflows, the protected lysine residue provides a controlled point for attachment chemistry, supporting consistent construction of peptide-based linkers and conjugate scaffolds used in biochemical assay development and materials-oriented research.
4. Pharmaceutical Intermediate Peptide Segments
Boc-L-Lys(Ns)-OH is also utilized in the preparation of protected peptide segments that function as intermediates in medicinal chemistry and pharmaceutical process development. Process and synthesis teams often incorporate this lysine building block when they need a protected, stable lysine unit that can be carried through intermediate stages before final functional-group adjustments are performed. The Ns-protected ε-amino group helps maintain compatibility with multi-step assembly and purification workflows, supporting the development of lysine-containing peptide intermediates used for further derivatization toward larger synthetic targets.
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