Tuning the cis/trans Conformer Ratio of Xaa-Pro Amide Bonds by Intramolecular Hydrogen Bonds: The Effect on PPII Helix Stability
作者:Michael Kuemin、Yvonne A. Nagel、Sabine Schweizer、Fabien W. Monnard、Christian Ochsenfeld、Helma Wennemers
DOI:10.1002/anie.201001851
日期:2010.8.23
ring pucker and a preference for the trans amide conformer are introduced as building blocks to tune the cis/trans amide conformer ratio in Xaa‐Pro bonds within peptides. Noncovalent interactions, such as hydrogen bonding between the substituent at C4 of the proline ring and the amide backbone are key for favoring or disfavoring the trans conformer (see picture).
Crystal structure of (4<i>S</i>
)-aminoproline: conformational insight into a pH-responsive proline derivative
作者:Christiane Siebler、Nils Trapp、Helma Wennemers
DOI:10.1002/psc.2734
日期:2015.3
The crystalstructure of a (4S)‐configured ammoniumproline derivative is presented. The trifluoroacetic acid salt of the acetylated methylester of (4S)‐aminoproline (Ac‐(4S)Amp‐OMe) crystallized as the trans conformer with a C(4)‐endo ring pucker. The high‐resolution structure shows typical parameters for a transannular H‐bond and an n → π* interaction between the adjacent amide and ester groups. The