Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia.
Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia; Department of Physical Biochemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
PLoS One. 2014 Jun 3;9(6):e98645. doi: 10.1371/journal.pone.0098645. eCollection 2014.
At present it is unclear which interactions in proteins reveal the presence of intermediate states, their stability and formation rate. In this study, we have investigated the effect of substitutions of hydrophobic amino acid residues in the hydrophobic core of protein and on its surface on a molten globule type intermediate state of apomyoglobin. It has been found that independent of their localization in protein, substitutions of hydrophobic amino acid residues do not affect the stability of the molten globule state of apomyoglobin. It has been shown also that introduction of a disulfide bond on the protein surface can stabilize the molten globule state. However in the case of apomyoglobin, stabilization of the intermediate state leads to relative destabilization of the native state of apomyoglobin. The result obtained allows us not only to conclude which mutations can have an effect on the intermediate state of the molten globule type, but also explains why the introduction of a disulfide bond (which seems to "strengthen" the protein) can result in destabilization of the protein native state of apomyoglobin.
目前尚不清楚蛋白质中的哪些相互作用揭示了中间状态的存在、它们的稳定性和形成速率。在这项研究中，我们研究了在肌红蛋白无血红素形式的类伸展球蛋白中间状态下，取代疏水核心和表面的疏水氨基酸残基对其的影响。结果发现，无论它们在蛋白质中的定位如何，取代疏水氨基酸残基都不会影响肌红蛋白无血红素形式的伸展球蛋白状态的稳定性。研究还表明，在蛋白质表面形成二硫键可以稳定伸展球蛋白状态。然而，在肌红蛋白无血红素的情况下，中间状态的稳定会导致肌红蛋白无血红素的天然状态相对不稳定。所得结果不仅使我们能够得出哪些突变可以对伸展球蛋白型中间状态产生影响的结论，而且还解释了为什么形成二硫键（似乎“增强”了蛋白质）会导致肌红蛋白无血红素的天然状态不稳定。
