Unfolding and refolding of cytochrome c driven by the interaction with lipid micelles
UNSPECIFIED. (2000) Unfolding and refolding of cytochrome c driven by the interaction with lipid micelles. PROTEIN SCIENCE, 9 (6). pp. 1194-1202. ISSN 0961-8368Full text not available from this repository.
Binding of native cyt c to L-PG micelles leads to a partially unfolded conformation of cyt c. This micelle-bound state has no stable tertiary structure. but remains as cu-helical as native cvt c in solution. In contrast, binding of the acid-unfolded cvt c to L-PG micelles induces folding of the polypeptide. resulting in a similar helical state to that originated from the binding of native cyt c to L-PG micelles. Far-ultraviolet (UV) circular dichroism (CD) spectra showed that this common micelle-associated helical state (H-L) has a native-like alpha-helix content, but is highly expanded without a tightly packed hydrophobic core, as revealed by tryptophan fluorescence, near-UV, and Sent CD spectroscopy. The kinetics of the interaction of native and acid-unfolded cyt c was investigated by stopped-flow tryptophan fluorescence. Formation of HL from the native state requires the disruption of the tightly packed hydrophobic core in the native protein. This micelle-induced unfolding of cyt c occurs at a rate similar to 0.1 s(-1), which is remarkably faster in the lipid environment compared with the expected rate of unfolding in solution. Refolding of acid-unfolded cyt c with L-PG micelles involves an early highly helical collapsed state formed during the burst phase (<3 ms), and the observed main kinetic event reports on the opening of this early compact intermediate prior to insertion into the lipid micelle.
|Item Type:||Journal Article|
|Subjects:||Q Science > QD Chemistry|
|Journal or Publication Title:||PROTEIN SCIENCE|
|Publisher:||CAMBRIDGE UNIV PRESS|
|Number of Pages:||9|
|Page Range:||pp. 1194-1202|
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