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Solvent‐induced β‐hairpin to helix conformational transition in a designed peptide
Author(s) -
Awasthi Satish K.,
Shankaramma S. C.,
Raghothama S.,
Balaram P.
Publication year - 2001
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/1097-0282(20010415)58:5<465::aid-bip1022>3.0.co;2-t
Subject(s) - chemistry , peptide , hydrogen bond , stereochemistry , solvent , peptide conformation , chemical shift , nuclear magnetic resonance spectroscopy , crystallography , helix (gastropod) , nuclear overhauser effect , polyproline helix , two dimensional nuclear magnetic resonance spectroscopy , molecule , organic chemistry , ecology , biochemistry , snail , biology
An octapeptide containing a central Aib–Gly– segment capable of adopting β‐turn conformations compatible with both hairpin (β II′ or β I′ ) and helical (β I ) structures has been designed. The effect of solvent on the conformation of the peptide Boc–Leu–Val–Val–Aib–Gly–Leu–Val–Val–OMe ( VIII ; Boc: t ‐butyloxycarbonyl; OMe: methyl ester) has been investigated by NMR and CD spectroscopy. Peptide VIII adopts a well‐defined β‐hairpin conformation in solvents capable of hydrogen bonding like (CD 3 ) 2 SO and CD 3 OH. In solvents that have a lower tendency to interact with backbone peptide groups, like CDCl 3 and CD 3 CN, helical conformations predominate. Nuclear Overhauser effects between the backbone protons and solvent shielding of NH groups involved in cross‐strand hydrogen bonding, backbone chemical shifts, and vicinal coupling constants provide further support for the conformational assignments in different solvents. Truncated peptides Boc–Val–Val–Aib–Gly–Leu–Val–Val–OMe ( VII ), Boc–Val–Val–Aib–Gly–Leu–Val–OMe ( VI ), and Boc–Val–Aib–Gly–Leu–OMe ( IV ) were studied in CDCl 3 and (CD 3 ) 2 SO by 500 MHz 1 H‐NMR spectroscopy. Peptides IV and VI show no evidence for hairpin conformation in both the solvents. The three truncated peptides show a well‐defined helical conformation in CDCl 3 . In (CD 3 ) 2 SO, peptide VII adopts a β‐hairpin conformation. The results establish that peptides may be designed, which are poised to undergo a dramatic conformational transition. © 2001 John Wiley & Sons, Inc. Biopolymers 58: 465–476, 2001