Protein Crystallization

Abstract

This chapter discusses purification and crystallization of protein. It also describes water-soluble proteins and the complexes they form with substrates, other proteins, and nucleic acids. It should also be realized from the outset that crystallization trials, when compared to other biochemical procedures, use a great deal of protein. The investigator must be prepared to purify a protein on a regular basis to have a reasonable chance of success. The purity required for crystallization varies for different proteins. Some can accommodate low levels of contamination while, for others, absolute purity is necessary. Proteins that appear as a single band on sodium dodecyl sulfate (SDS) gel electrophoresis are generally pure enough for initial trials. Certain aspects of protein structure are known to hinder crystal formation. Generally, compact rigid molecules are more amenable to crystallization than floppy ones; there have been many examples where crystals have been forthcoming only after removal of regions, such as irregular tails and small domains linked to the body of the protein by hingelike regions. Show more