Molten Globule-like State of Cytochrome C Under Conditions Simulating Those Near the Membrane Surface

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Alcohols, Circular Dichroism Spectroscopy, Membranes, Nucleic Acid Structure, Peptides and Proteins

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Methanol-induced conformational transitions in cytochromechave been studied by near- andfar-UV circular dichroism, Trp fluorescence, microcalorimetry, and diffusion measurements. The existenceof at least two cooperative stages of transition has been shown. At the first stage, the native protein istransformed into an intermediate which has only traces of tertiary structure, but has a native-like secondarystructure content and is relatively compact; i.e., it has properties of the molten globule state. On thesecond stage, the alcohol-induced molten globule is transformed into a more helical state, typical of proteinsat high alcohol concentrations. The conditions at which the alcohol-induced molten globule exists(moderately low pH and moderately low dielectric constant) could be similar to those existing nearnegatively charged membrane surfaces. Consequently, these results might explain how the molten globulestate can be achieved under physiological conditions.

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Citation / Publisher Attribution

Biochemistry, v. 35, issue 19, p. 6058-6063