Abstract

Guanidine hydrochloride (Gdn-HCl) is the most commonly used denaturant for proteins. Contrary to expectation, we found that Gdn-HCl at low concentrations refolds acid-unfolded apomyoglobin and cytochrome c, stabilizing the molten globule state, i.e. a compact denatured state with a significant amount of secondary structure, but substantially disordered tertiary structure. A further increase in Gdn-HCl concentration, above 1 M, caused co-operative unfolding of the molten globule state. Similar sequential folding and unfolding transitions were also observed at neutral pH with a synthetic amphiphilic peptide consisting of Lys and Leu residues, indicating the generality of the phenomenon. Although the Gdn-HCl-induced refolding and unfolding transitions were puzzling at first glance, we show that they are readily interpreted in terms of the differential action of Gdn-HCl. We also show that the comparison of the unfolding curves for the molten globule and native states provides a measure of the buried surface area upon formation of the molten globule state. Study holds ProTherm entries: 9244, 9245 Extra Details: apomyoglobin; cytochrome c; guanidine hydrochloride;,molten globule; protein folding

Submission Details

ID: VRhgqxv9

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:37 p.m.

Version: 1

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