Bychkova V E, Dujsekina A E, Klenin S I, Tiktopulo E I, Uversky V N, Ptitsyn O B
Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.
Biochemistry. 1996 May 14;35(19):6058-63. doi: 10.1021/bi9522460.
Methanol-induced conformational transitions in cytochrome c have been studied by near- and far-UV circular dichroism, Trp fluorescence, microcalorimetry, and diffusion measurements. The existence of at least two cooperative stages of transition has been shown. At the first stage, the native protein is transformed into an intermediate which has only traces of tertiary structure, but has a native-like secondary structure content and is relatively compact; i.e., it has properties of the molten globule state. On the second stage, the alcohol-induced molten globule is transformed into a more helical state, typical of proteins at high alcohol concentrations. The conditions at which the alcohol-induced molten globule exists (moderately low pH and moderately low dielectric constant) could be similar to those existing near negatively charged membrane surfaces. Consequently, these results might explain how the molten globule state can be achieved under physiological conditions.
通过近紫外和远紫外圆二色性、色氨酸荧光、微量量热法和扩散测量等方法，对甲醇诱导的细胞色素c构象转变进行了研究。结果表明，至少存在两个协同转变阶段。在第一阶段，天然蛋白质转变为一种中间体，该中间体仅具有微量的三级结构，但具有类似天然的二级结构含量且相对紧凑；也就是说，它具有熔球态的性质。在第二阶段，酒精诱导的熔球态转变为一种更螺旋的状态，这是高酒精浓度下蛋白质的典型状态。酒精诱导的熔球态存在的条件（适度低的pH值和适度低的介电常数）可能与带负电荷的膜表面附近存在的条件相似。因此，这些结果可能解释了在生理条件下如何实现熔球态。
