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Stereodependent and solvent‐specific formation of unusual β‐structure through side chain‐backbone H‐bonding in C4( S )‐(NH 2 /OH/NHCHO)‐L‐prolyl polypeptides
Author(s) -
Bansode Nitin D.,
Madhanagopal B.,
Sonar Mahesh V.,
Ganesh Krish.
Publication year - 2017
Publication title -
peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.22981
Subject(s) - chemistry , side chain , chain (unit) , solvent , stereochemistry , hydrogen bond , crystallography , polymer chemistry , molecule , organic chemistry , polymer , physics , astronomy
It is shown that C4( S )‐NH 2 /OH/NHCHO‐prolyl polypeptides exhibit PPII conformation in aqueous medium, but in a relatively hydrophobic solvent trifluoroethanol (TFE) transform into an unusual β‐structure. The stereospecific directing effect of H‐bonding in defining the specific structure is demonstrated by the absence of β‐structure in the corresponding C4( S )‐guanidinyl/(NH/O)‐acetyl derivatives and retention of β‐structure in C4( S )‐(NHCHO)‐prolyl polypeptides in TFE. The distinct conformations are identified by the characteristic CD patterns and supported by Raman spectroscopic data. The solvent dependent conformational effects are interpreted in terms of intraresidue H‐bonding that promotes PPII conformation in water, switching over to interchain H‐bonding in TFE. The present observations add a new design principle to the growing repertoire of strategies for engineering peptide secondary structural motifs for innovative nanoassemblies and new biomaterials.