NIST Center for Neutron Research, NIST, Gaithersburg, MD, 20899, USA.
Adv Exp Med Biol. 2017;1009:65-85. doi: 10.1007/978-981-10-6038-0_5.
Solution small-angle neutron scattering (SANS) combined with contrast variation provides information about the size and shape of individual components of a multi-component biological assembly, as well as the spatial arrangements between the components. The large difference in the neutron scattering properties between hydrogen and deuterium is key to the method. Isotopic substitution of deuterium for some or all of the hydrogen in either the molecule or the solvent can greatly alter the scattering properties of the biological assembly, often with little or no change to its biochemical properties. Thus, SANS with contrast variation provides unique information not easily obtained using other experimental techniques.If used correctly, SANS with contrast variation is a powerful tool for determining the solution structure of multi-component biological assemblies. This chapter discusses the principles of SANS theory that are important for contrast variation, essential considerations for experiment design and execution, and the proper approach to data analysis and structure modeling. As sample quality is extremely important for a successful contrast variation experiment, sample issues that can affect the outcome of the experiment are discussed as well as procedures used to verify the sample quality. The described methodology is focused on two-component biological complexes. However, examples of its use for multi-component assemblies are also discussed.
溶液小角中子散射（SANS）结合对比变化提供了关于多组分生物组装体中各个组分的大小和形状以及组分之间空间排列的信息。氢和氘之间中子散射性质的巨大差异是该方法的关键。在分子或溶剂中用氘部分或全部取代氢可以极大地改变生物组装体的散射性质，而其生化性质通常几乎没有变化。因此，具有对比变化的 SANS 提供了使用其他实验技术不易获得的独特信息。如果正确使用，具有对比变化的 SANS 是确定多组分生物组装体溶液结构的有力工具。本章讨论了对对比变化很重要的 SANS 理论原理、实验设计和执行的基本考虑因素以及数据分析和结构建模的适当方法。由于样品质量对于成功的对比变化实验极为重要，因此还讨论了可能影响实验结果的样品问题以及用于验证样品质量的程序。所描述的方法学侧重于二组分生物复合物。但是，也讨论了其用于多组分组装体的示例。
