Fmoc-Lys(Fmoc)-OPfp

Fmoc-Lys(Fmoc)-OPfp is a protected lysine-derived peptide building block in which the α-amino group is masked as an Fmoc carbamate and the ε-amino side chain is additionally protected as an Fmoc carbamate, while the carboxyl group is converted to an OPfp ester (pentafluorophenyl ester). The molecule contains two orthogonally removable Fmoc protecting groups that support stepwise peptide assembly under base-mediated deprotection, along with a highly activated OPfp ester that can participate in acyl transfer chemistry for rapid formation of amide bonds. The lysine backbone provides a stereogenic center that is retained from the chiral starting amino acid, enabling consistent stereochemical outcomes in peptide coupling and downstream fragment construction. The combination of dual N-protection and an activated carboxylate makes Fmoc-Lys(Fmoc)-OPfp a practical intermediate for protected amino acid synthesis, peptide coupling chemistry, and controlled functionalization of lysine-containing sequences.

1. Peptide Synthesis

Fmoc-Lys(Fmoc)-OPfp supports solid-phase or solution-phase peptide construction by pairing lysine's protected α- and ε-amino functionalities with an OPfp-activated carboxyl group that can undergo acylation to form the next peptide bond. The two Fmoc groups enable sequential deprotection and coupling strategies that preserve orthogonality between backbone elongation and side-chain handling, which is particularly relevant for lysine-rich peptides and for avoiding undesired cross-linking. The OPfp ester's leaving-group profile can facilitate formation of amide linkages under peptide-synthesis compatible conditions, leading to lysine incorporation with both amino termini protected during assembly. Downstream, the resulting Fmoc-protected lysine residues can be carried through further couplings to generate protected peptide intermediates and final peptide products after final deprotections.

2. Side-Chain Functionalization

Fmoc-Lys(Fmoc)-OPfp is suitable for side-chain functionalization workflows where lysine's ε-amino group must remain masked during early stages and then be selectively unmasked for conjugation chemistry. Dual Fmoc protection helps control the timing of ε-amino availability, enabling stepwise generation of lysine derivatives for subsequent attachment of linkers, affinity handles, or reactive groups while minimizing side reactions during peptide assembly. The OPfp ester functionality can be used in intermediate preparation to generate amide-linked fragments that retain the protected lysine scaffold for later derivatization. Resulting lysine-containing constructs can feed into peptidomimetic construction, chemical biology probes, or modular conjugates that require precise placement of a lysine side chain.

3. Bioconjugation Chemistry

Fmoc-Lys(Fmoc)-OPfp can be applied to bioconjugation-oriented synthesis of lysine-bearing linkers and conjugation intermediates where controlled amide formation and protected amine management are required. The OPfp ester enables formation of amide bonds to introduce the lysine unit into larger biomolecule-reactive scaffolds while maintaining Fmoc-protected amines to prevent premature cross-reactivity. The chiral lysine backbone provides a defined stereochemical element that can be carried into conjugates intended for structure-defined biochemical tools. After appropriate deprotection steps in the conjugation sequence, lysine-derived conjugation products can be generated for downstream labeling, affinity reagent preparation, or biomolecule modification chemistry.

4. Protected Amino Acid Chemistry

Fmoc-Lys(Fmoc)-OPfp functions as a protected amino acid derivative for preparing lysine-containing intermediates with controlled protecting-group patterns and activated carboxyl reactivity. The α-Fmoc and ε-Fmoc carbamates offer a clear protection strategy that supports predictable deprotection behavior and reduces the likelihood of side reactions during coupling and intermediate handling. The OPfp ester converts the carboxyl group into a reactive acyl donor, enabling transfer into amide-linked products without requiring immediate conversion to free carboxylates. Downstream, the compound can serve as a process chemistry intermediate for producing Fmoc-protected lysine building blocks, peptide coupling reagents, and defined lysine fragments used in fine chemical synthesis and peptide analog manufacturing.

5. Pharmaceutical Manufacturing

Fmoc-Lys(Fmoc)-OPfp is applicable to pharmaceutical manufacturing workflows that rely on protected amino acid and peptide intermediate quality for controlled synthesis of lysine-containing active ingredients or excipients. The dual Fmoc protection pattern supports robust protection-deprotection logic during manufacturing scale synthesis, while the OPfp ester supports efficient formation of amide-linked intermediates that can be carried through purification and downstream transformations. The lysine side chain architecture is compatible with manufacturing routes that require later functional group unveiling for controlled assembly of multicomponent molecules. Resulting intermediates can be used to construct peptide-like structures, peptidomimetic fragments, or defined lysine-containing building blocks that integrate into larger synthetic sequences in industrial chemical production.

1. Crystal Structure of BamB from Pseudomonas aeruginosa and Functional Evaluation of Its Conserved Structural Features

2. Immune-awakening Saccharomyces-inspired nanocarrier for oral target delivery to lymph and tumors

3. Adipose tissue is a key organ for the beneficial effects of GLP-2 metabolic function

4. Emu oil in combination with other active ingredients for treating skin imperfections

5. Proinsulin C-peptide and insulin: Limited pattern similarities of interest in inter-peptide interactions but no C-peptide effect on insulin and IGF-1 receptor signaling