Glycerol-induced formation of the molten globule from acid-denatured cytochrome c: implication for hierarchical folding |
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Authors: | Bongiovanni Cristiana Sinibaldi Federica Ferri Tommaso Santucci Roberto |
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Affiliation: | (1) Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Università di Roma Tor Vergata, V. Montpellier 1, 00133 Roma, Italy;(2) Dipartimento di Chimica, Università di Roma La Sapienza,, Roma, Italy |
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Abstract: | At high concentration (98% or higher, v/v), glycerol induces collapse of acid-denatured cytochrome c into a compact state, the GU state, showing a molten globule character. The GU state possesses a nativelike -helix structure but a tertiary conformation less packed with respect to the native state. The spectroscopic properties of the GU state closely resemble those of the molten globule stabilized by the organic solvent from the native protein (called the GN state), indicating that glycerol can stabilize the molten globule of cytochrome c either from the native or the acid-denatured protein. The GU and the GN states show spectroscopic (and, thus, structural) properties and stabilities comparable to those of molten globules stabilized by different effectors, despite the fact that the mechanisms involved in the molten globule formation may significantly differ. This implies in cytochrome c a hierarchy for the rupture (native-to-molten globule) or the formation (unfolded-to-molten globule) of intramolecular interactions leading to the stabilization of the molten globule state of the protein, independently from the effector responsible for the structural transition, in accord with the sequential model proposed by Englander and collaborators. |
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Keywords: | Cytochrome c molten globule glycerol circular dichroism |
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