Khorasanizadeh S, Peters I D, Roder H
Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.
Nat Struct Biol. 1996 Feb;3(2):193-205. doi: 10.1038/nsb0296-193.
To elucidate the kinetic importance of structural intermediates in single-domain proteins, we measured the effect of solution conditions and amino-acid changes at a central core residue of ubiquitin (Val 26) on the kinetics of folding and unfolding. Kinetic analysis in terms of a sequential three-state mechanism provides insight into the contribution of specific interactions within the ubiquitin core to the structural stability of the native and intermediate states. The observations that disruptive mutations and/or addition of denaturants result in an apparent two-state folding process with slower rates is explained by the destabilization of a partially folded intermediate, which is in rapid equilibrium with unfolded states. The model predicts that under sufficiently stabilizing conditions kinetic intermediates may become populated even for proteins showing apparent two-state kinetics.
为了阐明单结构域蛋白中结构中间体的动力学重要性，我们测量了溶液条件和泛素中心核心残基（Val 26）处的氨基酸变化对折叠和去折叠动力学的影响。根据连续三态机制进行的动力学分析，有助于深入了解泛素核心内特定相互作用对天然态和中间态结构稳定性的贡献。干扰性突变和/或添加变性剂会导致明显的两态折叠过程且速率较慢，这一现象可通过部分折叠中间体的去稳定化来解释，该中间体与未折叠状态处于快速平衡。该模型预测，在足够稳定的条件下，即使对于显示出明显两态动力学的蛋白质，动力学中间体也可能形成。
