Direct observation of protein refolding in mixed surfactant systems using contrast variation SANS

Protein renaturation in the presence of ionic-nonionic surfactant mixtures was recently reported for a handful of systems using spectroscopy and small-angle X-ray scattering. However, a mechanistic understanding of this phenomenon is still lacking, and the driving forces and conformational landscape of the protein are yet to be defined. In this experiment, we will use contrast-variation small-angle neutron scattering to elaborate a detailed model of interaction between human growth hormone, sodium dodecyl sulfate and dodecyl maltoside. The use of specific deuteration schemes will provide contrasts that discriminate the contribution to the scattering from different parts of the system, allowing to focus on structural changes on the protein and migration of surfactants between protein and micelles. This investigation is part of an industrial collaboration with Ferring Pharmaceuticals A/S.

近期已有研究借助光谱学与小角X射线散射（small-angle X-ray scattering）技术，在少数数种体系中报道了离子型-非离子型表面活性剂混合体系下的蛋白质复性现象。然而，目前仍缺乏对该现象的机制性认知，蛋白质的相互作用驱动力与构象景观尚未得到明确阐释。本实验将采用变对比度小角中子散射（contrast-variation small-angle neutron scattering）技术，构建人生长激素（human growth hormone）、十二烷基硫酸钠（sodium dodecyl sulfate）与十二烷基麦芽糖苷（dodecyl maltoside）之间相互作用的精细模型。通过特定的氘代标记方案，可获取区分体系不同组分对散射信号贡献的对比度数据，进而能够聚焦于蛋白质的结构变化以及表面活性剂在蛋白质与胶束间的迁移过程。本研究为与费林制药公司（Ferring Pharmaceuticals A/S）开展的工业合作项目的组成部分。