Fmoc-Homoarg(Pmc)-OH

Fmoc-Homoarg(Pmc)-OH is an Fmoc-protected homoarginine derivative bearing a side-chain guanidinium functionality masked as a Pmc (2,2,5,7,8-pentamethylchroman-6-sulfonyl) carbamoyl-protecting group. The structure contains a chiral homoarginine backbone with an extended methylene spacer relative to arginine, providing a distinct side-chain reach for peptide recognition and conformational effects. The orthogonally protected amine (Fmoc) and the acid-labile/orthogonally removable Pmc group support stepwise deprotection while preserving the guanidine functionality until late-stage peptide assembly. The molecule functions as a peptide building block with a protected, strongly basic side chain that can be converted to the free guanidinium for ionic interactions, salt-bridge formation, and nucleophilic/acid-base chemistry in downstream synthetic and biochemical studies.

1. Peptide Synthesis

Fmoc-Homoarg(Pmc)-OH is applied in solid-phase peptide synthesis where the Fmoc group enables controlled N-terminal deprotection and subsequent peptide coupling cycles. The homoarginine backbone and protected side-chain guanidine are positioned to introduce a longer, guanidinium-bearing side chain into peptide sequences, which can modulate local electrostatics and binding-site geometry. The Pmc-protected guanidine remains masked during chain elongation, supporting compatibility with common coupling conditions and minimizing side reactions of the basic functionality. The resulting peptides can be generated with a free guanidinium after final deprotection, enabling ionic interactions relevant to affinity probes, receptor-binding motifs, and peptide-based biochemical tools. Fmoc-homoarginine chemistry thus supports amino acid derivatization strategies that preserve orthogonality between backbone and side-chain protecting groups.

2. Chemical Biology Probes

Fmoc-Homoarg(Pmc)-OH is used in chemical biology workflows to construct guanidinium-rich peptide probes for studying electrostatic recognition and biomolecular interfaces. The protected guanidine side chain, once unmasked, can participate in strong hydrogen bonding and cationic interactions with nucleic acids, acidic protein surfaces, and glycosaminoglycans, making the homoarginine spacing a tunable parameter. The orthogonal protection pattern supports late-stage functionalization approaches, including conjugation handles introduced elsewhere in the peptide scaffold while keeping the guanidinium inert during assembly. The final deprotected peptides can serve as binding reagents, cell-penetrating motif variants, or competitive ligands in mechanistic assays. The compound's stereodefined amino acid framework also supports reproducible structure-function studies in peptide science and molecular recognition research.

3. Bioconjugation Chemistry

Fmoc-Homoarg(Pmc)-OH is suitable for bioconjugation chemistry where guanidinium-bearing peptide segments are required for stable association with negatively charged biomolecules or polymeric carriers. The Pmc-protected guanidine group provides a controlled activation point, allowing the free cationic functionality to be generated after peptide synthesis to match conjugation timing and minimize premature ion-mediated aggregation. The Fmoc-protected backbone supports incorporation into peptide linkers that can be subsequently reacted through orthogonal functional groups introduced during synthesis. The homoarginine side-chain extension can influence conjugate solubility, multivalent binding, and surface adsorption behavior in downstream materials and assay formats. Amino acid derivative construction using Fmoc and Pmc protecting-group strategies therefore supports controlled generation of cationic peptide linkers for applied biochemical and industrial R&D.

4. Peptidomimetics And SAR Studies

Fmoc-Homoarg(Pmc)-OH is employed in peptidomimetic and structure-activity relationship studies to build analogs that probe how side-chain length and guanidinium positioning affect binding and function. The extended homoarginine methylene spacing relative to arginine can alter the distance between the peptide backbone and the cationic guanidinium, influencing salt-bridge geometry and receptor-contact patterns. The protected guanidine enables systematic library synthesis where electrostatic motifs are introduced without interfering with iterative peptide coupling and protecting-group stability. The stereodefined chiral center supports consistent conformational preferences across analog series, improving interpretability of SAR outcomes. Downstream, deprotected guanidinium-containing analogs can be used for fragment linking, competitive binding panels, and mechanistic mapping of electrostatic determinants in biomolecular recognition.

5. Pharmaceutical Manufacturing Intermediates

Fmoc-Homoarg(Pmc)-OH can be used as a manufacturing-grade peptide intermediate for industrial peptide production where protected amino acids must withstand repeated coupling and deprotection steps under controlled process conditions. The Fmoc group provides a standard N-terminal protection strategy compatible with scalable solid-phase synthesis, while the Pmc-protected guanidine supports orthogonal handling of a strongly basic side chain that would otherwise complicate processing and purification. The homoarginine side chain length contributes to the controlled design of cationic peptide segments used in processable intermediates, including linkers and sequence-defined building blocks for larger peptide or peptidomimetic products. The orthogonality between backbone and side-chain protecting groups supports robust route design for stepwise deprotection and downstream formulation-oriented peptide generation. Industrially, this amino acid derivative supports reliable intermediate preparation for specialty chemical production and applied peptide manufacturing workflows.

6. Synthetic Organic Chemistry

Fmoc-Homoarg(Pmc)-OH is applicable in synthetic organic chemistry as a chiral, protected amino acid intermediate for constructing guanidinium-containing fragments beyond direct peptide assembly. The molecule's orthogonally protected amine (Fmoc) and masked guanidine (Pmc) enable selective deprotection sequences that can generate reactive cationic motifs at defined stages of synthesis. The chiral homoarginine backbone can be incorporated into non-peptidic scaffolds or used to prepare side-chain-functionalized intermediates through transformations that rely on the protected nature of the basic functionality. The extended side-chain geometry can be leveraged to tune ionic interaction profiles in synthetic ligands, affinity reagents, and polymer-binding units. The compound therefore serves as a stereodefined building block that supports protected amino acid chemistry and downstream derivatization strategies in fine chemical synthesis.

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