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[摘要]：The relevance of the alkali molten globule (B-state) to the folding pathway of cytochrome c has been studied further with the reduced state of the protein for which the B-state is prepared by ligating the ferrous heme iron with extrinsic CO under 1 mM gas concentration in the presence of NaCl. The CO derivative of ferrocytochrome c is desirable not only because it abrogates the interference of non-native heme ligands but the GdnHCl-unfolded protein refolds fast without deviating from the intrinsic folding pathway of the protein. Interstate folding-unfolding kinetics at alkaline and neutral pH conditions reveal that the B-state chain initially expands in the submillisecond regime in order to fold correctly to the native state. In this sense, it is an off-pathway nonproductive species which must dissipate some non-native elements before proceeding to fold. It is concluded that the alkali molten globule does not correspond to any possible transient structure in the folding pathway of cytochrome c. |
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