A Unique Molten Globule State Occurs during Unfolding of Cytochrome c by LiClO4 Near Physiological pH and Temperature: Structural and Thermodynamic Characterization
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- 作者：Beenu Moza ; Shabir Hussain Qureshi ; Asimul Islam ; Rajendrakumar Singh ; Farah Anjum ; Ali Akbar Moosavi-Movahedi ; and Faizan Ahmad
- 刊名：Biochemistry
- 出版年：2006
- 出版时间：April 11, 2006
- 年：2006
- 卷：45
- 期：14
- 页码：4695 - 4702
- 全文大小：115K
- 年卷期：v.45,no.14(April 11, 2006)
- ISSN：1520-4995
文摘
We have carried out denaturation studies of bovine cytochrome c (cyt c) by LiClO4 at pH 6.0and 25 
C by observing changes in difference molar absorbance at 400 nm (
400), mean residue ellipticitiesat 222 nm ([
]222) and difference mean residue ellipticity at 409 nm ([]409). The denaturation is athree-step process when measured by 400 and []409, and it is a two-step process when monitored by[]222. The stable folding intermediate state has been characterized by near- and far-UV circular dichroism,tryptophan fluorescence, 8-anilino-1-naphthalene sulfonic acid (ANS) binding, and intrinsic viscositymeasurements. A comparison of the conformational and thermodynamic properties of the LiClO4-inducedmolten globule (MG) state with those induced by other solvent conditions (e.g., low pH, LiCl, and CaCl2)suggests that LiClO4 induces a unique MG state, i.e., (i) the core in the LiClO4-induced state retains lesssecondary and tertiary structure than that in the MG states obtained in other solvent conditions, and (ii)the thermodynamic stability associated with the LiClO4-induced process, native state 
MG state, is thesame as that observed for each transition between native and MG states induced by other solvent conditions.
C by observing changes in difference molar absorbance at 400 nm (400), mean residue ellipticitiesat 222 nm ([]222) and difference mean residue ellipticity at 409 nm ([]409). The denaturation is athree-step process when measured by 400 and []409, and it is a two-step process when monitored by[]222. The stable folding intermediate state has been characterized by near- and far-UV circular dichroism,tryptophan fluorescence, 8-anilino-1-naphthalene sulfonic acid (ANS) binding, and intrinsic viscositymeasurements. A comparison of the conformational and thermodynamic properties of the LiClO4-inducedmolten globule (MG) state with those induced by other solvent conditions (e.g., low pH, LiCl, and CaCl2)suggests that LiClO4 induces a unique MG state, i.e., (i) the core in the LiClO4-induced state retains lesssecondary and tertiary structure than that in the MG states obtained in other solvent conditions, and (ii)the thermodynamic stability associated with the LiClO4-induced process, native state MG state, is thesame as that observed for each transition between native and MG states induced by other solvent conditions.