Evidence that the β‐Peptide 14‐Helix is Stabilized by β3‐Residues with Side‐Chain Branching Adjacent to the β‐Carbon Atom |
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Authors: | TamiL Raguse JonathanR Lai SamuelH Gellman |
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Institution: | Tami L. Raguse,Jonathan R. Lai,Samuel H. Gellman |
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Abstract: | Oligomers of β‐substituted β‐amino acids (‘β3‐peptides') are known to adopt a helical secondary structure defined by 14‐membered ring hydrogen bonds ('14‐helix'). Here, we describe a deca‐β3‐peptide, 1 , that does not adopt the 14‐helical conformation and that may prefer an alternative secondary structure. β3‐Peptide 1 is composed exclusively of residues with side chains that are not branched adjacent to the β‐C‐atom (β3‐hLeu, β3‐hLys, and β3‐hTyr). In contrast, an analogous β‐peptide, 2 , containing β3‐hVal residues in place of the β3‐hLeu residues of 1 , adopts a 14‐helical conformation in MeOH, according to CD data. These results illustrate the importance of side‐chain branching in determining the conformational preferences of β3‐peptides. |
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