Establishing Suitability of RNA Preparations for Crystallization: Determination of Polydispersity

Successful crystallization of ribozymes and ribozyme domains depends on covalent homogeneity of the sample, conformational homogeneity of the preparation, and an efficient and broad sampling of solution conditions where crystals might nucleate and grow. Chapter 38 presents methods to prepare multimilligram quantities of pure RNA, and Chapter 40 describes strategies for determining crystallization conditions. This chapter presents two methods to determine the conformational homogeneity (polydispersity) of RNA preparations. These methods have been successfully used to determine which of several related constructs of a given target molecule are likely to crystallize, enabling the experimenter to focus on the most promising candidate, and constitute an important step in a successful strategy for crystallization.