Unfolding of Green Fluorescent Protein mut2 in wet nanoporous silica gels

被引:62
作者
Campanini, B
Bologna, S
Cannone, F
Chirico, G
Mozzarelli, A
Bettati, S
机构
[1] Univ Parma, Dept Publ Hlth, I-43100 Parma, Italy
[2] Univ Parma, Dept Biochem & Mol Biol, I-43100 Parma, Italy
[3] Univ Parma, Natl Inst Phys Matter, I-43100 Parma, Italy
[4] Univ Milano Bicocca, Dept Phys, I-20126 Milan, Italy
[5] Univ Milano Bicocca, Natl Inst Phys Matter, I-20126 Milan, Italy
关键词
molecular crowding; protein folding; protein immobilization; encapsulation; fluorescence;
D O I
10.1110/ps.041190805
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Many of the effects exerted on protein structure, stability, and dynamics by molecular crowding and confinement in the cellular environment can be mimicked by encapsulation in polymeric matrices. We have compared the stability and unfolding kinetics of a highly fluorescent mutant of Green Fluorescent Protein, GFPmut2, in solution and in wet, nanoporous silica gels. In the absence of denaturant, encapsulation does not induce any observable change in the circular dichroism and fluorescence emission spectra of GFPmut2. In solution, the unfolding induced by guanidinium chloride is well described by a thermodynamic and kinetic two-state process. In the gel, biphasic unfolding kinetics reveal that at least two alternative conformations of the native protein are significantly populated. The relative rates for the unfolding of each conformer differ by almost two orders of magnitude. The slower rate, once extrapolated to native solvent conditions, superimposes to that of the single unfolding phase observed in solution. Differences in the dependence on denaturant concentration are consistent with restrictions opposed by the gel to possibly expanded transition states and to the conformational entropy of the denatured ensemble. The observed behavior highlights the significance of investigating protein function and stability in different environments to uncover structural and dynamic properties that can escape detection in dilute solution, but might be relevant for proteins in vivo.
引用
收藏
页码:1125 / 1133
页数:9
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