1-Aminocyclopentane-1-carboxylic acid is a cyclic, non-proteinogenic amino acid featuring a cyclopentane ring that constrains the backbone and places the amino and carboxyl groups on the same carbon (α-amino-α-carboxylic acid motif). The molecule contains a primary amino group and a carboxylic acid functional group, with the ring substituents providing a rigid, conformationally restricted side-chain environment that can influence peptide backbone geometry when incorporated into synthetic sequences. As a structurally constrained amino acid building block, it is used in peptide chemistry and chemical biology to prepare modified peptides and analogues for structure-property studies, conformational analysis, and analytical method development.
CAT No: CP19701
CAS No:52-52-8
Synonyms/Alias:cycloleucine;1-Aminocyclopentanecarboxylicacid;52-52-8;1-Aminocyclopentane-1-carboxylicacid;Cycloleucin;1-Amino-1-cyclopentanecarboxylicacid;1-Amino-cyclopentanecarboxylicacid;1-Amino-1-carboxycyclopentane;Cyclopentanecarboxylicacid,1-amino-;CYCLO-LEUCINE;NSC1026;CB1639;X201;UNII-0TQU7668EI;1-Aminocyclopentanecarboxylate;WR14,997;CHEMBL295830;CHEBI:40547;HSDB5195;NILQLFBWTXNUOE-UHFFFAOYSA-N;Amino-1-cyclopentanecarboxylicacid;EINECS200-144-6;MFCD00001381;SBB004230;1-aminocyclopentane(14c)carboxylicacid
1-Aminocyclopentane-1-carboxylic acid is a cyclic, conformationally constrained amino acid building block with a cyclopentane ring and an amino group at the quaternary carbon bearing the carboxylic acid. Its rigid scaffold makes it useful in medicinal chemistry and peptide research where backbone geometry and steric presentation are key design variables. As a free amino acid, it is typically handled as a synthetic intermediate for incorporation into larger molecules and for preparing analytical or reference materials that require this specific stereochemical and structural motif.
1. Peptidomimetic Building Blocks
1-Aminocyclopentane-1-carboxylic acid is used as a constrained residue in peptidomimetic and peptide-analog design, particularly when researchers aim to control local backbone conformation and side-chain sterics through a cycloalkyl framework. Medicinal chemistry and chemical biology groups incorporate this amino acid into short peptide scaffolds, constrained turn mimetics, and structure-activity relationship (SAR) series to probe how ring rigidity influences physicochemical properties and downstream binding hypotheses. Because it presents both an amino and a carboxylic acid functionality, it serves as a practical building block for coupling into larger fragments during library synthesis and custom peptide or analog manufacturing workflows.
2. Pharmaceutical Intermediate Development
1-Aminocyclopentane-1-carboxylic acid is also positioned as a pharmaceutical intermediate for preparing cycloalkyl-containing amide and amino-acid-derived fragments used in small-molecule and peptidomimetic programs. Process and R&D chemists commonly select this scaffold when a rigid, hydrophobic ring system is needed to tune molecular shape, steric bulk, and conformational effects in late-stage intermediate sets. In this role, the amino acid's defined functionality supports straightforward conversion into downstream coupling partners and protected derivatives used for sequential assembly of target structures in medicinal chemistry pipelines.
3. Analytical Reference Materials
1-Aminocyclopentane-1-carboxylic acid is frequently used to prepare analytical standards and method-development materials for chromatographic and mass spectrometric workflows involving cycloalkyl amino-acid motifs. Laboratories that quantify amino-acid-derived intermediates, monitor synthetic feedstocks, or validate sample prep for peptide-analog series rely on this compound as a structurally specific reference. Its distinct cyclic structure helps differentiate it from more common aliphatic amino acids during LC-MS method optimization and impurity profiling, supporting reproducible identification and calibration across synthesis and formulation-adjacent analytical tasks.
4. Chemical Biology Probe Synthesis
1-Aminocyclopentane-1-carboxylic acid is used in chemical biology projects that require incorporation of a conformationally constrained amino acid into probe scaffolds, such as binding probes, affinity handles, or substrate analogs. Researchers employ this building block to introduce a rigid cyclopentane element that can modulate how a probe presents functional groups to a biomolecular target or how it behaves in assay formats where steric context matters. In these workflows, the amino-acid functional groups enable coupling into probe precursors and subsequent attachment of detection or affinity moieties as part of custom probe construction for biochemical and biophysical screening studies.
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