1yyx
From Proteopedia
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The solution structure of a redesigned apocytochrome B562 (Rd-apocyt b562) at 2.8M urea
Overview
The absence of detectable kinetic and equilibrium folding intermediates by, optical probes is commonly taken to indicate that protein folding is a, two-state process. However, for some small proteins with apparent, two-state behavior, unfolding intermediates have been identified in, native-state hydrogen exchange or kinetic unfolding experiments monitored, by nuclear magnetic resonance. Rd-apocytochrome b(562), a four-helix, bundle, is one such protein. Here, we found another unfolding intermediate, for Rd-apocytochrome b(562). It is based on a cooperative transition of, (15)N chemical shifts of amide protons as a function of urea, concentrations before the global unfolding. We have solved the, high-resolution structure of the protein at 2.8 M urea, which is after, this cooperative transition but before the global unfolding. All four, helices remained intact, but a number of hydrophobic core residues, repacked. This intermediate provides a possible structural interpretation, for the kinetic unfolding intermediates observed using nuclear magnetic, resonance methods for several proteins and has important implications for, theoretical studies of protein folding.
About this Structure
1YYX is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Detection and structure determination of an equilibrium unfolding intermediate of Rd-apocytochrome b562: native fold with non-native hydrophobic interactions., Feng H, Vu ND, Bai Y, J Mol Biol. 2004 Nov 5;343(5):1477-85. PMID:15491625
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