APIS group Blog

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Bicyclic Pyrrolidine-Isoxazoline γ Amino Acid: A Constrained Scaffold for Stabilizing α-Turn Conformation in Isolated Peptides

amino acids have tremendously expanded the folding possibilities of peptides and peptide mimics. While α,α-disubstituted and β-amino acids are widely studied, γ-derivatives have been less exploited. Here we report the conformational study on the...

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Fluoro-Aryl Substituted α,β2,3-Peptides in the Development of Foldameric Antiparallel β-Sheets: A Conformational Study

α,β2,3-Disteroisomeric foldamers of general formula Boc(S-Ala-β-2R,3R-Fpg)nOMe or Boc(S-Ala-β-2S,3S-Fpg)nOMe were prepared from both enantiomers of syn H-2-(2-F-Phe)-h-PheGly-OH (named β-Fpg) and S-alanine. Our peptides show two appealing features for biomedical applications: the presence of fluorine, attractive for non-covalent interactions,...

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From glucose to enantiopure morpholino β-amino acid: a new tool for stabilizing γ-turns in peptide

A new cyclic enantiopure β-amino acid, named β-Morph, containing the morpholino ring, was obtained in gram scale starting from an α-D-glucopyranose enantiopure material, focusing on the “environmental sustainability” concept. A series of ultrashort model...

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Tetrahydro‑4H‑(pyrrolo[3,4‑d]isoxazol-3-yl)methanamine: A Bicyclic Diamino Scaffold Stabilizing Parallel Turn Conformations

A tetrahydro-4H-(pyrrolo[3,4-d]isoxazol-3-yl)methanamine
scaffold was designed as a diamino derivative to stabilize parallel turn
conformations. Its synthesis took advantage of a [1,3]-dipolar cycloaddition
reaction between the nitrile oxide derived from the inexpensive enantiopure Lphenylalanine
and N-benzyl-3-pyrroline. Two diastereoisomers were formed,
whose distribution depends on the selected base. 3aR,6aS-Isomer is favored in
organic bases, which formation is driven by π-interactions. However, the above
interactions were significantly prevented using an inorganic base due to the
chaotropic effect of the cation, decreasing the amount of the above isomer.
Finally, we demonstrated that this isomer is able to stabilize parallel turn
conformations when inserted in short peptide sequences.