Fmoc-L-His-OAll

Fmoc-L-His-OAll is an Fmoc-protected L-histidine derivative bearing an OAll (allyl ester) on the carboxylate, combining a stable N-protection strategy with an orthogonally removable C-terminal ester handle. The molecule contains the imidazole side chain characteristic of histidine, enabling pH-dependent protonation and nucleophilic or electrophilic participation in subsequent derivatization and peptide microenvironment tuning. The chiral center at the α-carbon is fixed in the L-configuration, supporting stereochemically defined peptide bond formation under standard coupling conditions. The orthogonal Fmoc/allyl protection pattern supports controlled deprotection sequences, while the ester functionality can serve as a synthetic intermediate for downstream carboxylate activation or conversion to alternative terminal groups.

1. Peptide Synthesis

Fmoc-L-His-OAll is used in automated and manual peptide building workflows where Fmoc protection enables stepwise N-terminal deprotection and coupling while the allyl ester supports C-terminal functional control. The histidine imidazole side chain can be managed through imidazole-compatible conditions, and the protected backbone facilitates reliable amide bond formation at the α-carboxylate position. The OAll group can be removed under orthogonal conditions to generate a free carboxylic acid for chain extension, capping, or conversion to other terminal motifs. The resulting peptide products and peptide intermediates are suitable for constructing histidine-containing sequences used in biochemical research and peptide chemistry.

2. Side-Chain Functionalization

Fmoc-L-His-OAll is applied in chemical biology and peptide derivatization strategies that exploit the imidazole functionality of histidine for selective modification and recognition. The maintained stereochemical integrity of the L-amino acid backbone supports predictable incorporation into peptide scaffolds before or after side-chain transformation. The orthogonal protection scheme allows the Fmoc group to be removed for assembly while preserving the ability to later manipulate the C-terminus via allyl ester deprotection and subsequent activation. Imidazole-bearing intermediates generated from this amino acid ester can be used to access conjugation-ready derivatives, affinity handles, or metal-binding motifs for downstream molecular design.

3. Bioconjugation Chemistry

Fmoc-L-His-OAll is suitable for bioconjugation workflows that require histidine-containing peptide fragments as conjugation substrates or linker components. The Fmoc-protected amine supports controlled incorporation into peptide linkers, while the allyl ester provides a handle for orthogonal conversion to carboxylate forms that can be activated for coupling to amines, hydrazides, or other nucleophiles. The imidazole side chain can participate in coordination chemistry or nucleophilic reactivity depending on the conjugation environment, enabling construction of conjugates with histidine-mediated binding or functional microenvironments. The resulting conjugation intermediates can be used to generate labeled or functional biomolecule analogs for biochemical assays and materials-oriented studies.

4. Process Chemistry Intermediate

Fmoc-L-His-OAll is relevant to process chemistry and fine chemical synthesis as a protected histidine building block that supports scalable protection/deprotection logic in manufacturing routes. The Fmoc group provides robust N-protection during handling and coupling operations, while the OAll ester offers an orthogonal C-terminal transformation point that can be integrated into stepwise production sequences. The defined L-stereochemistry reduces the risk of stereochemical drift during intermediate preparation and supports consistent downstream peptide assembly. The compound can serve as a controllable intermediate for producing histidine-containing peptide building blocks, standardized peptide fragments, and manufacturing feedstocks used in applied peptide production.

5. Analytical Research Standards

Fmoc-L-His-OAll is used in analytical research settings to prepare reference materials and method development standards for monitoring peptide coupling, deprotection, and side-chain integrity. The combination of Fmoc protection and an allyl ester enables characteristic mass spectrometric and chromatographic signatures that can help track intermediate states during peptide synthesis workflows. The histidine imidazole moiety contributes diagnostic behavior across pH-dependent conditions, supporting analytical discrimination of histidine-containing species. The compound can be employed to generate calibration or verification standards for characterizing protected amino acid derivatives, peptide intermediates, and orthogonally deprotected products in method development and quality-oriented studies.

1. Extended exenatide administration enhances lipid metabolism and exacerbates pancreatic injury in mice on a high fat, high carbohydrate diet

2. Cell-based adhesion assays for isolation of snake venom’s integrin antagonists

3. Immune responses to peptides containing homocitrulline or citrulline in the DR4-transgenic mouse model of rheumatoid arthritis

4. SERS spectrum of the peptide thymosin‐β4 obtained with Ag nanorod substrate

5. Therapeutic potential of an intestinotrophic hormone, glucagon-like peptide 2, for treatment of type 2 short bowel syndrome rats with intestinal bacterial and fungal dysbiosis