Basova Liana V, Tiktopulo Elisaveta I, Kutyshenko Victor P, Mauk A Grant, Bychkova Valentina E
Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290 Russia.
Biochim Biophys Acta. 2008 Apr;1778(4):1015-26. doi: 10.1016/j.bbamem.2007.12.028. Epub 2008 Jan 17.
The influence of charged phospholipid membranes on the conformational state of the water-soluble fragment of cytochrome b5 has been investigated by a variety of techniques at neutral pH. The results of this work provide the first evidence that aqueous solutions with high phospholipid/protein molar ratios (pH 7.2) induce the cytochrome to undergo a structural transition from the native conformation to an intermediate state with molten-globule like properties that occur in the presence of an artificial membrane surface and that leads to binding of the protein to the membrane. At other phospholipid/protein ratios, equilibrium was observed between cytochrome free in solution and cytochrome bound to the surface of vesicles. Inhibition of protein binding to the vesicles with increasing ionic strength indicated for the most part an electrostatic contribution to the stability of cytochrome b5-vesicle interactions at pH 7.2. The possible physiological role of membrane-induced conformational change in the structure of cytochrome b5 upon the interaction with its redox partners is discussed.
在中性pH条件下，运用多种技术研究了带电荷的磷脂膜对细胞色素b5水溶性片段构象状态的影响。这项工作的结果首次证明，具有高磷脂/蛋白质摩尔比的水溶液（pH 7.2）会诱导细胞色素从天然构象转变为具有类熔球性质的中间状态，这种状态出现在人工膜表面存在时，并导致蛋白质与膜结合。在其他磷脂/蛋白质比例下，观察到溶液中游离的细胞色素与结合在囊泡表面的细胞色素之间存在平衡。随着离子强度增加，蛋白质与囊泡的结合受到抑制，这在很大程度上表明在pH 7.2时静电作用对细胞色素b5 - 囊泡相互作用的稳定性有贡献。文中还讨论了膜诱导的细胞色素b5构象变化在其与氧化还原伙伴相互作用时对细胞色素b5结构可能具有的生理作用。
