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Temperature‐Dependent NMR and CD Spectra of β ‐Peptides: On the Thermal Stability of β ‐Peptide Helices – Is the Folding Process of β ‐Peptides Non‐cooperative?
Author(s) -
Gademann Karl,
Jaun Bernhard,
Seebach Dieter,
Perozzo Remo,
Scapozza Leonardo,
Folkers Gerd
Publication year - 1999
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/(sici)1522-2675(19990113)82:1<1::aid-hlca1>3.0.co;2-n
Subject(s) - chemistry , peptide , folding (dsp implementation) , crystallography , protein secondary structure , thermal stability , circular dichroism , helix (gastropod) , hydrophobic effect , stereochemistry , organic chemistry , biochemistry , ecology , snail , electrical engineering , biology , engineering
Temperature‐dependent NMR and CD spectra of methanol solutions of a β ‐hexapeptide and of a β ‐heptapeptide at temperatures between 298 and 393 K are reported. They establish the fact that the 3 14 ‐helical secondary structures of the two β ‐peptides, 1 and 2 , do not `melt' in the temperature range investigated. This is in sharp contrast to the behavior of the helices of α ‐peptides and proteins which undergo cooperative unfolding (`denaturing') upon heating. A non‐cooperative mechanism is proposed, with a stepwise, rather than an `un‐zipping' opening of H‐bonded rings ( cf . Fig. 6 ). The experimental results are regarded as evidence that, of the three effects which have been identified as contributing to the stability of β ‐peptide helices, i.e. , H‐bonding, hydrophobic interactions, and ethane staggering, the latter one is predominant.