Screening and optimization methods for nonautomated crystallization laboratories.

Crystallization of biological macromolecules is becoming increasingly automated. However, for various reasons, many laboratories still perform at least some aspects of the work manually. A typical crystallization project entails two distinct steps: screening and optimization. The aim of the initial phase is to screen the many parameters affecting crystallization, and as broadly as possible. If any promising conditions are found, these are optimized with other protocols. This chapter describes procedures for manual screening by the vapor diffusion and microbatch methods in 96- and 24-well plate formats. For optimization, several protocols are presented, including grid and additive screens, seeding, and manipulation of the drop kinetics. The scoring of crystallization results and methods for distinguishing protein and salt crystals are also discussed in this chapter.