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The Design of α/β‐Peptides: Study on Three‐Residue Turn Motifs and the Influence of Achiral Glycine on Helix and Turn
Author(s) -
Sharma Gangavaram V. M.,
Chandramouli Nagula,
Basha Shaik Jeelani,
Nagendar Pendem,
Ramakrishna Kallaganti V. S.,
Sarma Akella V. S.
Publication year - 2011
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.201000438
Subject(s) - turn (biochemistry) , residue (chemistry) , hydrogen bond , helix (gastropod) , chemistry , stereochemistry , peptide , glycine , amino acid , amino acid residue , side chain , alpha helix , helix turn helix , protein secondary structure , crystallography , peptide sequence , circular dichroism , biochemistry , molecule , biology , organic chemistry , ecology , snail , gene , polymer , repressor , transcription factor
Novel three‐residue helix‐turn secondary structures, nucleated by a helix at the N terminus, were generated in peptides that have ‘β‐Caa‐ L ‐Ala‐ L ‐Ala,’ ‘β‐Caa‐ L ‐Ala‐γ‐Caa,’ and ‘β‐Caa‐ L ‐Ala‐δ‐Caa’ (in which β ‐ Caa is C‐linked carbo‐β‐amino acid, γ ‐ Caa is C‐linked carbo‐γ‐amino acid, and δ‐Caa is C‐linked carbo‐δ‐amino acid) at the C terminus. These turn structures are stabilized by 12‐, 14‐, and 15‐membered (mr) hydrogen bonding between NH( i )/CO( i +2) ( i +2 is the last residue in the peptide) along with a 7‐mr hydrogen bond between CO( i )/NH( i +2). In addition , a series of α/β‐peptides were designed and synthesized with alternating glycine (Gly) and ( S )‐β‐Caa to study the influence of an achiral α‐residue on the helix and helix‐turn structures. In contrast to previous results, the three ‘β–α–β’ residues at the C terminus (α‐residue being Gly) are stabilized by only a 13‐mr forward hydrogen bond, which resembles an α‐turn. Extensive NMR spectroscopic and molecular dynamics (MD) studies were performed to support these observations. The influence of chirality and side chain is also discussed.