Equilibrium and non-equilibrium conformations of peptides in lipid bilayers.
Biophys Chem
; 65(2-3): 205-10, 1997 Apr 22.
Article
em En
| MEDLINE
| ID: mdl-9175271
ABSTRACT
A synthetic, hydrophobic, 27-amino-acid-residue peptide 'K27', modelled on the trans-membrane domain of the slow voltage-gated potassium channel, IsK, has been incorporated into a lipid bilayer and its conformational properties studied using FT-IR spectroscopy. The conformation following reconstitution is found to be dependent on the nature of the solvent employed. When the reconstitution is conducted by solvent evaporation from a methanol solution, aggregates comprised of beta-strands are stabilised and their concentration is essentially invariant with time. By contrast, when trifluoroethanol is used, the initial conformation of the peptide is alpha-helical. This then relaxes to an equilibrium state between alpha-helices and beta-strands. The alpha-helix-to beta-strand conversion rate is relatively slow, and this allows the kinetics to be studied by FT-IR spectroscopy. The reverse process is much slower but again can be demonstrated by FT-IR. Thus, it appears that a true equilibrium structure can only be achieved by starting with peptide in the alpha-helical conformation. We believe this result should be of general validity for hydrophobic peptide reconstitution. The implications for conformational changes in membrane proteins are discussed.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Peptídeos
/
Canais de Potássio
/
Bicamadas Lipídicas
Idioma:
En
Revista:
Biophys Chem
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
Reino Unido
País de publicação:
HOLANDA
/
HOLLAND
/
NETHERLANDS
/
NL
/
PAISES BAJOS
/
THE NETHERLANDS