L-Cyclopentylalanine is a proteinogenic amino acid belonging to the aliphatic/aromatic amino acid family, featuring an α-amino and α-carboxylate framework with a cyclopentyl side chain instead of the benzyl group of phenylalanine. The molecule bears a primary amino group and a carboxylic acid functionality, with the side chain presenting a hydrophobic, conformationally constrained cyclopentyl ring that can influence packing and local steric environment in peptide backbones. As a free amino acid, it is used as a building block in peptide synthesis and structure-activity studies where hydrophobicity and side-chain shape are varied, and it can also serve as a reference substrate in analytical or enzyme-substrate investigations focused on amino-acid recognition.
CAT No: CP21401
L-Cyclopentylalanine is an L-configured amino acid bearing a cyclopentyl side chain that provides a conformationally constrained, hydrophobic residue for peptide and protein engineering workflows. The molecule contains a primary amino group and a carboxylic acid functionality, enabling standard amino-acid coupling chemistry while also supporting selective protection of the amine and controlled activation of the acid. The stereogenic center at the alpha carbon enforces defined chirality during synthesis and downstream incorporation into peptide sequences. As a chiral amino acid building block and intermediate, L-cyclopentylalanine can be converted into protected derivatives and amino-acid esters for stepwise assembly, derivatization, and analytical method development.
1. Peptide Synthesis
L-Cyclopentylalanine is applied in peptide synthesis as an L-amino-acid residue for constructing hydrophobic segments in peptides and peptidomimetics. The side-chain cyclopentyl group behaves as a nonpolar, sterically defined substituent that can influence folding propensity and local conformational preferences when incorporated by standard amide bond formation. The free amino and carboxy groups support conversion to N-protected forms and C-terminal activation strategies, enabling compatibility with common peptide coupling protocols and orthogonal deprotection schemes. The resulting cyclopentylalanine-containing peptides can serve as sequence-defined probes, scaffold components, or SAR-focused analogs in medicinal chemistry and chemical biology programs.
2. Side-Chain Functionalization
L-Cyclopentylalanine is utilized for amino acid derivatization where the cyclopentyl side chain serves as a hydrophobic handle for further chemical modification. The amino acid backbone can be protected as needed so that side-chain transformations occur without disrupting peptide coupling readiness, while the carboxyl functionality can be maintained as an activated ester or converted to an amide after functional group installation. Derivatives prepared from the amino acid can be used to tune lipophilicity, steric bulk, and conformational constraints in fragment-based molecular design and peptidomimetic construction. Downstream functionalized products can also serve as intermediates for generating libraries of analogs used in structure-activity relationship studies and binding-site mapping.
3. Chemical Biology Probes
L-Cyclopentylalanine is suitable for chemical biology applications that require incorporation of a defined hydrophobic residue into protein-interacting peptides, enzyme substrates, or binding probes. The stereochemically defined alpha center helps maintain consistent spatial presentation of the amino acid during conjugation to biomolecular targets or during peptide-based recognition experiments. The amino and carboxyl functionalities can be selectively protected to allow controlled formation of amide linkages to linkers, tags, or reporter moieties used in biomolecule labeling workflows. Cyclopentylalanine-containing constructs can function as sequence-controlled probes for studying molecular recognition, membrane association tendencies, or hydrophobic pocket engagement in vitro.
4. Protein Engineering Inputs
L-Cyclopentylalanine is applied as a chiral building block for protein engineering and peptide-based materials where hydrophobic residues with constrained geometry are required. The L-configuration supports stereodefined incorporation into designed sequences, and the cyclopentyl side chain can provide a distinct steric and hydrophobic profile relative to linear alkyl analogs. N-/C-terminal derivatization strategies can be used to prepare peptide fragments for assembly into larger constructs or for generating reference standards in protein modification studies. Prepared derivatives and peptide intermediates derived from L-cyclopentylalanine can be employed to tune folding behavior, stability proxies, and interaction surfaces in applied protein and biomolecular engineering contexts.
5. Process Chemistry Intermediate
L-Cyclopentylalanine is used as a process chemistry intermediate for manufacturing amino-acid derivatives, including protected amino acids and amino acid esters required for downstream fine chemical synthesis. The presence of an alpha-amino group and a carboxylic acid enables robust protection/activation logic that can be integrated into scalable synthetic routes for peptide building blocks and specialty intermediates. The cyclopentyl side chain contributes chemical stability under typical protection and activation conditions while maintaining a defined stereocenter that is critical for consistent product identity across batch production. L-cyclopentylalanine-derived intermediates can be routed into peptide coupling supply chains, analytical reference material preparation, and industrial-scale synthesis of amino-acid-containing specialty chemicals.
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