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Three‐Residue Turn in β‐Peptides Nucleated by a 12/10 Helix
Author(s) -
Sharma Gangavaram V. M.,
Yadav Thota Anupama,
Marumudi Kanakaraju,
Thodupunuri Prashanth,
Reddy Pothula Purushotham,
Kunwar Ajit C.
Publication year - 2014
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201402465
Subject(s) - residue (chemistry) , turn (biochemistry) , helix (gastropod) , chemistry , side chain , hydrogen bond , stereochemistry , monomer , peptide , amino acid residue , alpha helix , furan , oxygen , crystallography , circular dichroism , peptide sequence , organic chemistry , biochemistry , molecule , polymer , biology , ecology , snail , gene
A new three‐residue turn in β peptides nucleated by a 12/10‐mixed helix is presented. In this design, β peptides were derived from the 1:1 alternation of C‐linked carbo‐β‐amino acid ester [BocNH‐( R )‐β‐Caa (r) ‐OMe] (Boc= tert ‐butyloxycarbonyl), which consisted of a D ‐ ribo furanoside side chain, and β‐hGly residues. The hexapeptide with ( R )‐β‐Caa (r) at the N terminus showed the ‘turn’ stabilized by a 14‐membered NH(4) ⋅⋅⋅ CO(6) hydrogen bond at the C terminus nucleated by a robust 12/10‐mixed helix, thus providing a ‘helix‐turn’ (HT) motif. The turn and the helix were additionally stabilized by intraresidue electrostatic interaction between the furan oxygen in the carbohydrate side chain and NH in the backbone. However, the hexapeptide with a β‐hGly residue at the N terminus demonstrated the presence of a 10/12 helix through its entire length, which again showed the intraresidue interaction between NH and furan oxygen. The intraresidue NH ⋅⋅⋅ OMe electrostatic interactions observed in the monomer, however, were absent in the peptides.