Infrared study of the stability and folding kinetics of a 15-residue beta-hairpin.
J Am Chem Soc
; 125(50): 15388-94, 2003 Dec 17.
Article
em En
| MEDLINE
| ID: mdl-14664583
ABSTRACT
The thermal stability and folding kinetics of a 15-residue beta-hairpin (SESYINPDGTWTVTE) have been studied by using infrared (IR) spectroscopy coupled with laser-induced temperature-jump (T-jump) technique for rapid folding-unfolding initiation. An alternative method based on analyzing IR difference spectra was also introduced to obtain thermodynamic properties of beta-sheets, which complements the commonly used circular dichroism (CD) and fluorescence techniques. Equilibrium IR measurements indicate that the thermal unfolding of this beta-hairpin is fairly broad. However, it can be described by a two-state transition with a thermal melting temperature of approximately 29 degrees C. Time-resolved IR measurements following a T-jump, probed at 1634 cm(-1), indicate that the folding of this beta-hairpin follows first-order kinetics and is amazingly fast. At 300 K, the folding time is approximately 0.8 micros, which is only 2-3 times slower than that of alpha-helix formation. Additionally, the energetic barrier for folding is small (approximately 2 kcal mol(-1)). These results, in conjunction with results from other studies, support a view that the details of native contacts play a dominant role in the kinetics of beta-hairpin folding.
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01-internacional
Base de dados:
MEDLINE
Idioma:
En
Ano de publicação:
2003
Tipo de documento:
Article