Helix-coil transition theories. Are they correct?

Andrzej Bierzyński, Krzysztof Pawłowski

Research output: Contribution to journalReview articlepeer-review

10 Scopus citations

Abstract

Principles of contemporary theoretical description of α-helix formation by polypeptide chains in water solution are shortly presented and critically discussed. The theory treats the unfolded state of a peptide as "random coil" - an ideal conformation quite distant from reality. We suggest that for this reason the helix propagation parameters of amino-acid residues, determined using series of model peptides with different sequential patterns, are not the same. Interpretation of the so called "nucleation parameter" is erroneous. In fact, it is not determined by the helix nucleation process but rather by a specific situation of residues at the helix N- and C-termini, and it strongly depends on solvation of their NH and CO groups, respectively. Consequently, helical segments with terminal sequences dominated by residues with strongly hydrophobic, bulky side chains can be very unstable. We postulate that an unexpectedly high stability of very short, pre-nucleated helices studied by us arises from a "helix end separation effect": separated helix termini are better solvated than when they overlap each other. Because of this effect, helix initiation may be much more difficult than predicted by the theoretical "helix nucleation parameters".

Original languageEnglish (US)
Pages (from-to)423-432
Number of pages10
JournalActa Biochimica Polonica
Volume44
Issue number3
DOIs
StatePublished - 1997
Externally publishedYes

Keywords

  • Hydration
  • Peptides folding
  • Random coil
  • Thermodynamics
  • α-helix

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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