在其pK(a)时，十二烷基硫酸钠可诱导出一种独特的核糖核酸酶A中间体。
A distinct intermediate of RNase A is induced by sodium dodecyl sulfate at its pK(a).
作者信息
Moosavi-Movahedi A A, Gharanfoli M, Nazari K, Shamsipur M, Chamani J, Hemmateenejad B, Alavi M, Shokrollahi A, Habibi-Rezaei M, Sorenson C, Sheibani N
机构信息
Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
出版信息
Colloids Surf B Biointerfaces. 2005 Jul 10;43(3-4):150-7. doi: 10.1016/j.colsurfb.2005.04.008.
The chemical denaturation of RNase A was found to be mediated by sodium dodecyl sulfate (SDS) at various pH. The characterization of the unfolding pathway was investigated by spectrophotometry and differential scanning calorimetry (DSC), and was analyzed by multivariate curve resolution (MCR) as a chemometric method. The spectrophotometric titration curve of RNase A upon interaction with SDS indicated a distinct complex intermediate in glycine buffer at pH 3.3. This was accompanied with the catalytic activation of the enzyme and was concurrent with maximum population of the intermediate, determined by MCR. This was confirmed by the DSC profile of RNase A in the presence of SDS, indicated by two transitions in thermal unfolding. The kinetic data on the unfolding process of RNase A upon addition of SDS showed a two-phase pathway under the same conditions. The intermediate appeared at low pH especially at the pK(a) of SDS (pH 3.3). These results provide strong evidence of the influence of low pH (around the pK(a) of SDS) on the existence of an intermediate upon interaction of RNase A with SDS.
研究发现，在不同pH值下，核糖核酸酶A（RNase A）的化学变性由十二烷基硫酸钠（SDS）介导。通过分光光度法和差示扫描量热法（DSC）研究了其去折叠途径的特征，并采用多元曲线分辨（MCR）这一化学计量学方法进行分析。RNase A与SDS相互作用时的分光光度滴定曲线表明，在pH 3.3的甘氨酸缓冲液中存在一个明显的复合中间体。这伴随着酶的催化活化，并且与通过MCR确定的中间体的最大丰度同时出现。SDS存在下RNase A的DSC曲线也证实了这一点，热去折叠过程中有两个转变峰。添加SDS后RNase A去折叠过程的动力学数据表明，在相同条件下该过程呈现两相途径。中间体在低pH值时出现，尤其是在SDS的pK(a)（pH 3.3）时。这些结果提供了有力证据，证明低pH值（接近SDS的pK(a)）对RNase A与SDS相互作用时中间体的存在有影响。
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