Size and shape of detergent micelles determined by small-angle x-ray scattering
Size and shape of detergent micelles determined by small-angle x-ray scattering
复制标题
DOI：
10.1021/jp073016l
复制
发表时间：
2007-11-01
影响因子：
3.3
通讯作者：
Doniach, Sebastian
中科院分区：
文献类型：
--
作者：
Lipfert, Jan;Columbus, Linda;Doniach, Sebastian
我们提出了一个系统的分析的聚集数和形状的胶束形成的九个洗涤剂常用的膜蛋白的研究。报道了具有8和9个烷基碳的葡萄糖苷（OG/NG）、具有10和12个烷基碳的麦芽糖苷和磷酸胆碱的小角X射线散射测量结果（DM/DDM和FC-10/FC-1,2）、1，2-二己酰-sn-甘油-磷酸胆碱（DHPC）、1-棕榈酰-2羟基-sn-甘油-3-[磷酸-rac-（1 -甘油）]（LPPG）和3-[（3-胆酰胺丙基）二甲基铵-1-丙磺酸酯（CHAPS）。的SAXS强度很好地描述了两个组件的椭球模型，与一个致密的外壳对应的洗涤剂的头部基团和一个电子密度较低的疏水性核心。这些模型提供了胶束大小和形状的中间分辨率视图。此外，我们表明，Guinier分析的前向散射强度可以用来获得一个独立的和无模型的测量胶束聚集数和回转半径。这种方法的优点是易于推广到蛋白质-洗涤剂复合物，其中简单的几何模型是不适用的。此外，我们发现散射强度中第二个最大值的位置可以直接测量整个胶束核心的特征头基-头基间距。我们的胶束聚集数和尺寸的结果同意有利的文献值，只要他们是可用的。我们重新测定了FC-10、FC-12、DM、LPPG和CHAPS胶束的形状，FC-10和OG的聚集数约为1.25。分别是50和250。结合起来，这些数据提供了胶束形成的决定因素的全面看法，并作为一个起点，相关的洗涤剂性能与洗涤剂-蛋白质相互作用。
We present a systematic analysis of the aggregation number and shape of micelles formed by nine detergents commonly used in the study of membrane proteins. Small-angle X-ray scattering measurements are reported for glucosides with 8 and 9 alkyl carbons (OG/NG), maltosides and phosphocholines with 10 and 12 alkyl carbons (DM/DDM and FC-IO/FC-12), 1,2-dihexanoyl-sn-glycero-phosphocholine (DHPC), I-palmitoyl-2hydroxy-sn-glycero-3-[phospho-rac-(1 -glycerol)] (LPPG), and 3-[(3-cholamidopropyl)dimethylammoniol-lpropane sulfonate (CHAPS). The SAXS intensities are well described by two-component ellipsoid models, with a dense outer shell corresponding to the detergent head groups and a less electron dense hydrophobic core. These models provide an intermediate resolution view of micelle size and shape. In addition, we show that Guinier analysis of the forward scattering intensity can be used to obtain an independent and model-free measurement of the micelle aggregation number and radius of gyration. This approach has the advantage of being easily generalizable to protein-detergent complexes, where simple geometric models are inapplicable. Furthermore, we have discovered that the position of the second maximum in the scattering intensity provides a direct measurement of the characteristic head group-head group spacing across the micelle core. Our results for the micellar aggregation numbers and dimensions agree favorably with literature values as far as they are available. We de novo determine the shape of FC-10, FC-12, DM, LPPG, and CHAPS micelles and the aggregation numbers of FC-10 and OG to be ca. 50 and 250, respectively. Combined, these data provide a comprehensive view of the determinants of micelle formation and serve as a starting point to correlate detergent properties with detergent -protein interactions.