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Stop‐flow kinetics studies of the interaction of surfactant, sodium dodecyl sulfate, with acid‐denatured cytochrome c
Author(s) -
Xu Qi,
Keiderling Timothy A.
Publication year - 2006
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.20926
Subject(s) - sodium dodecyl sulfate , chemistry , kinetics , circular dichroism , cytochrome c , fluorescence , pulmonary surfactant , molten globule , micelle , folding (dsp implementation) , cytochrome , photochemistry , chromatography , biophysics , crystallography , organic chemistry , biochemistry , aqueous solution , enzyme , quantum mechanics , electrical engineering , mitochondrion , biology , engineering , physics
Interactions of sodium dodecyl sulfate (SDS) at submicellar and micellar concentration, with the globular protein, horse heart cytochrome c, at low pH have been shown to stabilize two molten globule‐like intermediates. These dynamic studies were performed using far‐UV, near‐UV, and Soret‐band circular dichroism (CD) as well as fluorescence methods. Stopped‐flow CD and fluorescence studies of acid‐denatured cytochrome c refolding with SDS were performed at both submicellar and micellar concentrations. Distinctive refolding mechanisms (from analysis of both CD and fluorescence) were found under these two conditions, and an obvious refolding intermediate was evident in the fluorescence traces. In addition, stopped‐flow CD in the Soret region showed multistep kinetics, suggesting that the spectral changes in this region are not only solvent effect related but also connected with the change of secondary structure. A possible folding mechanism is proposed to rationalize the kinetics results. Proteins 2006. © 2006 Wiley‐Liss, Inc.