Fmoc-His(1-Trt)-OPfp is a protected histidine derivative designed for peptide chemistry, featuring a histidine side chain bearing a Trt (trityl) protecting group on the imidazole nitrogen along with an N-terminal Fmoc (9-fluorenylmethoxycarbonyl) group. The molecule also incorporates a C-terminal OPfp ester, where OPfp denotes an active pentafluorophenyl ester that presents a carboxylate-derived leaving group for subsequent acyl transfer chemistry, while the amino acid framework retains the histidine α-amino and α-carboxyl connectivity masked by the protecting groups. In synthesis and labeling workflows, this compound functions as an acylating intermediate to enable stepwise construction of peptide bonds under controlled chemoselectivity, with the orthogonal Fmoc/Trt/OPfp protection pattern supporting selective deprotection and coupling sequence design.
Fmoc-His(1-Trt)-OPfp is an Fmoc-protected histidine derivative bearing a Trt-protected Nπ side chain and an OPfp ester at the carboxylate, forming a chiral, peptide-coupling-ready amino acid building block. The molecule combines an Fmoc carbamate on the α-amino group with a side-chain imidazole protected as a Trt (trityl) ether, reducing undesired coordination and side reactions during peptide assembly. The OPfp leaving group activates the carboxylate for acyl transfer under peptide coupling conditions, enabling rapid formation of amide bonds while maintaining orthogonal protection of the imidazole functionality. The stereochemical integrity at the α-carbon is preserved through the protected amino acid format, and the presence of multiple aromatic protecting elements supports controlled deprotection strategies in downstream synthesis.
1. Peptide Synthesis
Fmoc-His(1-Trt)-OPfp is used in peptide synthesis workflows where histidine incorporation with protected Nπ functionality is required to maintain side-chain integrity during chain elongation. The Fmoc group enables standard N-terminal deprotection to generate a reactive amine for subsequent coupling, while the Trt protection on the imidazole reduces nucleophilicity and metal-binding behavior that can complicate coupling and purification. The OPfp ester at the carboxyl terminus supports efficient acyl transfer to form peptide bonds under amide coupling conditions, allowing incorporation into linear peptides, protected peptide fragments, and segment coupling strategies. Downstream deprotection can regenerate the histidine imidazole for further functionalization or for biochemical recognition studies, aligning the building block with peptide science and protected amino acid synthesis.
2. Peptidomimetics Construction
Fmoc-His(1-Trt)-OPfp serves as a chiral amino acid intermediate for peptidomimetic construction where controlled histidine side-chain presentation is needed for receptor binding motifs and metal coordination sites. The protected imidazole (Trt) and the Fmoc-protected α-amino group provide orthogonal handles that can be manipulated to introduce histidine-containing motifs into peptide analogs without premature side-chain reactivity. The OPfp ester enables conversion into amide-linked analogs, supporting fragment assembly toward constrained scaffolds, stapled peptides, or heteroatom-containing mimetics where the imidazole must remain masked until late-stage synthesis. Resulting derivatives can be advanced into structure-activity relationship studies by enabling consistent histidine positioning and controlled deprotection to expose the functional imidazole for binding-site evaluation.
3. Chemical Biology Probes
Fmoc-His(1-Trt)-OPfp is applied in chemical biology research to generate histidine-bearing peptide conjugation precursors and labeling reagents with controlled imidazole availability. The Trt-protected imidazole helps prevent side-chain participation during peptide assembly and purification, while the Fmoc strategy supports stepwise construction of defined peptide sequences that later yield an exposed Nπ imidazole for specific interactions. The OPfp ester format supports formation of amide bonds to attach linkers, affinity tags, or reactive handles, enabling downstream installation of bioconjugation motifs such as electrophiles, chelators, or capture groups. The resulting histidine-containing conjugates can be used as biochemical research intermediates for studying molecular recognition, metal-dependent binding, or protein-peptide interaction mechanisms.
4. Protein Engineering
Fmoc-His(1-Trt)-OPfp supports protein engineering and peptide-based domain design by enabling incorporation of histidine residues into engineered polypeptide segments with predictable protection behavior. The orthogonal protection scheme, combining Fmoc on the α-amino group and Trt on the imidazole nitrogen, helps maintain sequence fidelity during synthesis and reduces competing reactions associated with unprotected imidazole during fragment assembly. The OPfp ester enables peptide bond formation suitable for generating histidine-containing peptide segments that can serve as building blocks for larger constructs, including designed binding interfaces and metal-coordinating elements. After deprotection, the restored histidine imidazole can participate in biochemical assays, enabling controlled exploration of sequence-dependent recognition and catalytic-site mimicry in applied protein design workflows.
5. Pharmaceutical Manufacturing
Fmoc-His(1-Trt)-OPfp is relevant to pharmaceutical manufacturing and fine chemical production where histidine-containing peptide intermediates must be synthesized with robust protection and reproducible coupling chemistry. The Fmoc/Trt orthogonality supports manufacturing-compatible deprotection sequencing, allowing the imidazole to remain masked during upstream coupling steps and to be revealed under controlled conditions for final product formation. The OPfp ester provides an activated carboxyl functionality that can be employed in process chemistry to streamline peptide coupling steps toward defined intermediates used in peptide drug substance or peptide-based intermediate generation. Downstream, the protected amino acid format supports scalable synthesis of histidine-containing sequences that can be further processed into drug-relevant peptide fragments, analytical standards, or formulation precursors within industrial peptide supply chains.
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