SOLUTION X-RAY SCATTERING STUDIES ON PROTEIN INTERACTION

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 利用小角散射对蛋白质在溶液中的结构因子进行系统研究，可以提取蛋白质的静电性质以及蛋白质与蛋白质的相互作用。我们对溶菌酶的相互作用进行了初步研究，这在过去的一些已发表的蛋白质相互作用研究中得到了广泛的研究。在这类研究中，有必要在大范围的蛋白质和盐浓度范围内进行小角X射线散射测量。用稀释的蛋白质样品来获得形状因子，需要高浓度的溶液来确定结构因子。在没有盐的情况下，蛋白质分子之间的静电相互作用占主导地位，而吸引人的短程电势在高盐浓度下变得可检测到。我们的初步结果表明，在BL4-2中，我们可以在低至0.5 mg/ml的浓度下测定溶菌酶形状因子。我们能够克服以前用溶菌酶观察到的辐射损伤问题，使用流动细胞和溶液分配器相结合。我们计划研究甘油的影响，甘油是一种已知有助于将辐射损害降至最低的试剂，对蛋白质相互作用潜力的影响。还将研究L-精氨酸和L-谷氨酸的作用，据报道，这两种物质共同改善蛋白质的溶解性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Systematic studies of the structure factor of a protein in solution by small angle scattering can extract electrostatic properties of the protein and protein-protein interaction. We conducted initial studies on the interactions of lysozyme, which has been extensively studied in the past in a number of published protein interaction studies. It is necessary to carry out small angle X-ray scattering measurements over a wide range of protein and salt concentrations in this class of studies. Dilute protein samples are used to obtain the form factor and highly concentrated solutions are needed for determining the structure factor. In the absence of salt the electrostatic interactions among protein molecules dominates while the attractive short-range potentials become detectable at high salt concentrations. Our preliminary results demonstrate that we can determine the lysozyme form factor at concentrations as low as 0.5 mg/ml at BL 4-2. We were able to overcome radiation damage problems we had previously observed with lysozyme, using the flow cell in combination with the solution dispenser. We plan on studying the effects of glycerol, an agent known to help minimize radiation damage on the protein interaction potential. Also studied will be the effects of L-Arg and L-Glu, which together have been reported to improve protein solubility.