Helix-coil transition theories. Are they correct?

• Autorzy: Bierzynski A. , Pawlowski K.
• Języki publikacji: EN

Abstrakty

EN

Principles of contemporary theoretical description of a-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".

Słowa kluczowe

EN

thermodynamics; random coil; polypeptide chain; peptide folding; hydration; alpha-helix

• Wydawca: -
• Czasopismo: Acta Biochimica Polonica
• Rocznik: 1997
• Tom: 44
• Numer: 3
• Opis fizyczny: p.423-432,fig.

Twórcy

autor

Bierzynski A.

• Polish Academy of Sciences, A.Pawinskiego 5a, 02-106 Warsaw, Poland

autor

Pawlowski K.

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