ULTRAFAST MEASUREMENTS OF PROTEIN FOLDING USING SAXS

我们建议应用快速连续流技术 进行小角X射线散射（SAXS）测量， 在1-50毫秒的时间范围内的蛋白质折叠的阶段。 常规 停流SAXS技术的时间分辨率>50 ms， 死区时间为10 ms。使用喷射混合器，死区时间为 减小到1 ms，并且应实现1 ms的时间分辨率。 采用小角X射线散射和快速连续混合相结合的方法 技术，我们将测量未折叠蛋白质的压缩速率 当它突然被置于自然条件下时。 SAXS是唯一 已知时间分辨技术给出了总体尺寸和形状 蛋白质构象状态的指示。 SAXS数据可能是 用于确定回转半径和获得形状 可以从Kratky图推断出的信息， 分布函数 停流的最早数据点 技术通常显示出相对紧凑结构 未折叠的状态。 随着时间分辨率的大幅提高 和减少的死时间，我们将能够研究压实率， 在重新折叠的早期阶段彻底进行。

We propose the application of the rapid continuous flow technique to make small angle x-ray scattering (SAXS) measurements of the early stages of protein folding in the 1-50 ms time range. The conventional stopped-flow SAXS technique results in a time resolution of >50 ms and a dead time of 10 ms. Using a jet-mixer, the dead time will be reduced to 1 ms and a time resolution of 1 ms should be achieved. Using the combination of SAXS and the rapid continuous mixing technique, we will measure an unfolded protein's rate of compaction when it is suddenly placed under native conditions. SAXS is the only known time-resolved technique which gives overall size and shape indication of the conformational state of a protein. SAXS data may be used to determine the radius of gyration and to obtain shape information which may be inferred from the Kratky plot and the pair distribution function. The earliest data points for the stopped-flow technique usually show a relatively compact structure as compared to the unfolded state. With the dramatically improved time resolution and reduced dead time, we will be able to study the rate of compaction thoroughly at the early stages of refolding.