Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Govindpura, Bhopal, Madhya Pradesh, India.
Phys Chem Chem Phys. 2013 Jun 21;15(23):9375-83. doi: 10.1039/c3cp50207d. Epub 2013 May 10.
The mechanism by which the protein bovine serum albumin undergoes unfolding induced by the anionic surfactant sodium dodecyl sulphate (SDS) and then the subsequent refolding brought in by β-Cyclodextrin (β-CD) was studied by steady-state fluorescence, time resolved measurements and Circular Dichroism (CD) spectroscopy. The prominent findings of this investigation are (i) SDS unfolds the protein in a sequential manner passing through three different phases of binding of SDS followed by a saturation phase; (ii) the refolding process is initiated through inclusion/removal of SDS molecules by β-CD and hence this also seems to happen in a phased manner; (iii) the process of refolding seems to be reversible to the unfolding process but the protein does not regain all its structure on refolding; (iv) however, CD results reveal almost 100% recovery of the secondary structure lost during SDS induced unfolding. We have conclusively proved that there is a marginal structural gain of the native protein at low surfactant concentration and β-CD also induces a marginal structural loss to the native protein. The unfolding process induced by SDS seems to be spontaneous and the binding of SDS to BSA is rather strong, as revealed by thermodynamic parameters.
通过稳态荧光、时间分辨测量和圆二色性（CD）光谱研究了蛋白质牛血清白蛋白（BSA）在阴离子表面活性剂十二烷基硫酸钠（SDS）诱导下展开，然后由β-环糊精（β-CD）引发的随后折叠的机制。该研究的主要发现是：（i）SDS 以顺序方式使蛋白质展开，经历 SDS 结合的三个不同阶段，然后达到饱和阶段；（ii）折叠过程是通过β-CD 包含/去除 SDS 分子引发的，因此这似乎也以分相方式发生；（iii）折叠过程似乎对展开过程是可逆的，但蛋白质在折叠后不会恢复其所有结构；（iv）然而，CD 结果表明，在 SDS 诱导的展开过程中丢失的二级结构几乎可以 100%恢复。我们已经确凿地证明，在低表面活性剂浓度下，天然蛋白质存在微小的结构增益，β-CD 也会导致天然蛋白质的微小结构损失。SDS 诱导的展开过程似乎是自发的，SDS 与 BSA 的结合相当强，这可以从热力学参数中看出。
