Stereospecific Synthesis of Conformationally Constrained γ-Amino Acids: New Foldamer Building Blocks That Support Helical Secondary Structure
作者:Li Guo、Yonggui Chi、Aaron M. Almeida、Ilia A. Guzei、Brian K. Parker、Samuel H. Gellman
DOI:10.1021/ja907233q
日期:2009.11.11
A highly stereoselective synthesis of novel cyclically constrained gamma-amino acid residues is presented. The key step involves organocatalytic Michael addition of an aldehyde to 1-nitrocyclohexene. After aldehyde reduction, this approach provides optically active beta-substituted delta-nitro alcohols (96-99% ee), which can be converted to gamma-amino acid residues with a variety of substituents at
Helical secondary structures in 2:1 and 1:2 α/γ-peptide foldamers
作者:Li Guo、Weicheng Zhang、Ilia A. Guzei、Lara C. Spencer、Samuel H. Gellman
DOI:10.1016/j.tet.2012.01.079
日期:2012.6
Oligomers containing both α- and γ-aminoacid residues in a 1:1 alternating pattern have recently been shown by several research groups to adopt helical secondary structures. We have begun to explore the folding behavior of oligomers with different α-residue/γ-residue backbone patterns. Previously we reported that the γ-aminoacids bearing a cyclohexyl constraint at the Cβ–Cγ bond and a variable side
Helix Formation in Preorganized β/γ-Peptide Foldamers: Hydrogen-Bond Analogy to the α-Helix without α-Amino Acid Residues
作者:Li Guo、Aaron M. Almeida、Weicheng Zhang、Andrew G. Reidenbach、Soo Hyuk Choi、Ilia A. Guzei、Samuel H. Gellman
DOI:10.1021/ja103233a
日期:2010.6.16
We report the first high-resolution structural data for the beta/gamma-peptide 13-helix (i,i+3 C=O center dot center dot center dot H-N H-bonds), a secondary structure that is formed by oligomers with a 1:1 alternation of beta- and gamma-amino acid residues. Our characterization includes both crystallophaphic and 2D NMR data. Previous studies suggested that beta/gamma-peptides constructed from conformationally flexible residues adopt a different helical secondary structure in solution. Our design features preorganized beta- and gamma-residues, which strongly promote 13-helical folding by the 1:1 beta/gamma backbone.