作者:Shuqing Wu、Joann J. Lu、Shili Wang、Kristy L. Peck、Guigen Li、Shaorong Liu
DOI:10.1021/ac071055n
日期:2007.10.1
A novel staining method and the associated fluorescent dye were developed for protein analysis by capillary SDS-PAGE. The method strategy is to synthesize a pseudo-SDS dye and use it to replace some of the SDS in SDS−protein complexes so that the protein can be fluorescently detected. The pseudo-SDS dye consists of a long, straight alkyl chain connected to a negative charged fluorescent head and binds to proteins just as SDS. The number of dye molecules incorporated with a protein depends on the dye concentration relative to SDS in the sample solution, since SDS and dye bind to proteins competitively. In this work, we synthesized a series of pseudo-SDS dyes, and tested their performances for capillary SDS-PAGE. FT-16 (a fluorescein molecule linked with a hexadodecyl group) seemed to be the best among all the dyes tested. Although the numbers of dye molecules bound to proteins (and the fluorescence signals from these protein complexes) were maximized in the absence of SDS, high-quality separations were obtained when co-complexes of SDS−protein−dye were formed. The migration time correlates well with protein size even after some of the SDS in the SDS−protein complexes was replaced by the pseudo-SDS dye. Under optimized experimental conditions and using a laser-induced fluorescence detector, limits of detection of as low as 0.13 ng/mL (bovine serum albumin) and dynamic ranges over 5 orders of magnitude in which fluorescence response is proportional to the square root of analyte concentration were obtained. The method and dye were also tested for separations of real-world samples from E. coli.
开发了一种新型染色方法及其相关的荧光染料,用于通过毛细管SDS-PAGE进行蛋白质分析。该方法的策略是合成伪-SDS染料,并用其替代SDS−蛋白质复合物中的部分SDS,以便能够荧光检测蛋白质。伪-SDS染料由长的直链烷基和带负电荷的荧光头连接而成,其与蛋白质的结合方式与SDS类似。与蛋白质结合的染料分子数量依赖于样品溶液中染料相对于SDS的浓度,因为SDS和染料是竞争性结合蛋白质。在本研究中,我们合成了一系列伪-SDS染料,并测试了它们在毛细管SDS-PAGE中的表现。FT-16(一个连接了十六烷基的荧光素分子)在所有测试的染料中似乎是最好的。尽管在没有SDS的情况下与蛋白质结合的染料分子数量(以及这些蛋白质复合物的荧光信号)达到了最大,但当形成SDS−蛋白质−染料的共复合物时,仍然获得了高质量的分离。即使在SDS−蛋白质复合物中的部分SDS被伪-SDS染料替代,迁移时间与蛋白质大小的相关性仍然良好。在优化的实验条件下,使用激光诱导荧光检测器,检测限低至0.13 ng/mL(牛血清白蛋白),并获得了大于5个数量级的动态范围,其中荧光响应与待测物浓度的平方根成正比。这种方法和染料也在分离来自大肠杆菌的实际样本中进行了测试。