Fmoc-L-Pro-OSu is an Fmoc-protected L-proline derivative in which the carboxyl group is converted to a reactive N-hydroxysuccinimide (OSu) ester, while the pyrrolidine side chain remains characteristic of proline and the molecule retains an amino functionality. The structure contains an Fmoc carbamate on the α-amino group and an activated ester at the carboxyl position, providing a nucleophilic acyl transfer handle that can undergo amide-bond formation with amines under appropriate conditions. In peptide chemistry and bioconjugation workflows, Fmoc-L-Pro-OSu is employed as an activated amino acid building block to support coupling steps in the preparation of Fmoc-based peptide intermediates and other amide-linked derivatives.
CAT No: CP25149
CAS No:109074-94-4
Synonyms/Alias:Fmoc-Pro-OSu;109074-94-4;AmbotzFAA6500;MolPort-008-267-787;AKOS016003145;ZINC100004958;AK-81221;KB-281492;ST24030723;K-0625;N-alpha-(9-Fluorenylmethyloxycarbonyl)-L-prolinesuccinimidylester;2,5-Dioxo-1-pyrrolidinyl1-[(9H-fluoren-9-ylmethoxy)carbonyl]-L-prolinate
Chemical Name:N-alpha-(9-Fluorenylmethyloxycarbonyl)-L-proline succinimidyl ester
Fmoc-L-Pro-OSu is an Fmoc-protected L-proline N-[(9H-fluoren-9-yl)methoxycarbonyl] amino acid activated as an N-hydroxysuccinimide ester (OSu), featuring a stereodefined pyrrolidine ring and a reactive ester linkage at the carboxylate position. The compound combines an orthogonally removable Fmoc group for solid-phase peptide synthesis with an OSu leaving group that readily participates in amide bond formation under peptide coupling conditions. The chiral center at the proline backbone is preserved through the activation step, supporting stereochemically consistent incorporation into peptide sequences and peptidomimetic scaffolds. The activated carboxyl functionality enables downstream conversion into peptide bonds, while the Fmoc protection strategy supports controlled N-terminal handling during iterative chain assembly.
1. Peptide Synthesis
Fmoc-L-Pro-OSu is used in peptide building workflows where OSu activation supports rapid amide bond formation to introduce L-proline at a defined position in a growing chain. The Fmoc-protected nitrogen and the stereochemically fixed proline ring enable compatibility with standard peptide coupling logic, including N-terminal deprotection and subsequent coupling cycles. The activated ester can react with amine nucleophiles to form peptide linkages while maintaining the proline stereochemistry that governs conformational constraints in peptides. The resulting proline-containing peptide fragments can be carried forward to longer sequences, enabling structure-focused peptide construction for biochemical research and scaffold development.
2. Side-Chain Functionalization
Fmoc-L-Pro-OSu is applied in chemical modification strategies that require controlled installation of a proline-derived amide handle onto biomolecule fragments or synthetic polymers. The OSu ester reacts with primary amines to form stable amide bonds, while the Fmoc group provides a protected amino acid identity that can be carried through intermediate steps before N-terminal unmasking. The rigid proline ring can influence local geometry in conjugates, which may be relevant for designing constrained linkers, receptor-binding motifs, or conformationally restricted peptidomimetics. Downstream derivatization can generate proline-bearing conjugates for mapping reaction specificity, building affinity ligands, or preparing functional materials with amide-linked architectures.
3. Bioconjugation Chemistry
Fmoc-L-Pro-OSu is suitable for bioconjugation workflows where OSu activation enables coupling to lysine-like primary amines on peptides, proteins, or amine-functionalized surfaces. The compound's carboxyl activation supports formation of amide-linked conjugates without requiring separate coupling reagents for the ester-to-amide transformation step. The presence of the Fmoc group allows the conjugate to be handled as a protected intermediate, supporting staged deprotection when unmasking or further peptide assembly is needed. The resulting amide-linked proline incorporation can support chemical biology experiments such as linker optimization, conjugate library preparation, and controlled construction of peptide-based probes.
4. Protected Amino Acid Intermediates
Fmoc-L-Pro-OSu functions as a protected amino acid intermediate for manufacturing and synthesis planning where Fmoc protection and OSu activation are combined in a single chiral reagent. The Fmoc group provides an N-protecting strategy that can be removed orthogonally during peptide assembly, while the OSu ester serves as a reactive handle for downstream coupling to amines. The stereodefined L-proline framework allows consistent incorporation into peptide building block preparations and peptidomimetic analog synthesis, supporting reproducible stereochemical outcomes across batches. The compound can be employed as a process chemistry intermediate for producing proline-containing peptide fragments, activated amino acid stocks, and downstream coupling-ready materials.
5. Analytical Research Standards
Fmoc-L-Pro-OSu is utilized in analytical research contexts where defined, Fmoc-protected proline chemistry supports method development for peptide coupling monitoring and intermediate characterization. The OSu activation provides a distinct chemical signature associated with activated carboxyl species, while the Fmoc chromophore supports UV-active detection and chromatographic tracking in workflows that include peptide synthesis intermediates. The chiral, stereochemically fixed proline component can serve as a reference for assessing coupling selectivity and stereochemical integrity in proline-containing sequences. The compound's structured functional groups make it suitable for generating characterized standards, calibrants, or internal reference materials used in peptide chemistry analytics and process development studies.
6. Pharmaceutical Manufacturing
Fmoc-L-Pro-OSu can be applied in pharmaceutical manufacturing-oriented peptide process development where controlled proline incorporation and protected amino acid handling are required for reproducible intermediate generation. The Fmoc-protected nitrogen supports N-terminal management during sequential assembly, while the OSu ester enables coupling to amine-bearing substrates under peptide-compatible conditions. The constrained proline ring can be relevant for producing conformationally defined peptide intermediates used in downstream drug substance synthesis and related peptide manufacturing steps. The compound's role as an activated, stereodefined building block supports industrially relevant fine chemical synthesis and process chemistry intermediate preparation for peptide-based workflows.
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