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Evidence that the β ‐Peptide 14 ‐Helix is Stabilized by β 3 ‐Residues with Side‐Chain Branching Adjacent to the β ‐Carbon Atom
Author(s) -
Raguse Tami L.,
Lai Jonathan R.,
Gellman Samuel H.
Publication year - 2002
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200290001
Subject(s) - chemistry , side chain , branching (polymer chemistry) , peptide , stereochemistry , hydrogen bond , helix (gastropod) , protein secondary structure , carbon atom , ring (chemistry) , crystallography , molecule , organic chemistry , biochemistry , polymer , ecology , snail , biology
Oligomers of β ‐substituted β ‐amino acids (‘ β 3 ‐peptides') are known to adopt a helical secondary structure defined by 14‐membered ring hydrogen bonds (' 14 ‐helix'). Here, we describe a deca‐ β 3 ‐peptide, 1 , that does not adopt the 14 ‐helical conformation and that may prefer an alternative secondary structure. β 3 ‐Peptide 1 is composed exclusively of residues with side chains that are not branched adjacent to the β ‐C‐atom ( β 3 ‐hLeu, β 3 ‐hLys, and β 3 ‐hTyr). In contrast, an analogous β ‐peptide, 2 , containing β 3 ‐hVal residues in place of the β 3 ‐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 β 3 ‐peptides.