Strategies for protein separation
The analysis of proteins, whether on a small or large scale, requires methods for the separation of protein mixtures into their individual components. Protein separation methods can be placed on a sliding scale from fully selective to fully nonselective. Selective methods aim to isolate individual proteins from a mixture usually by exploiting very speciﬁc properties such as their binding speciﬁcity or biochemical function. Such methods are particularly useful for studying protein interactions or functions, and are discussed in more detail in Chapter 7. They also form the basis of protein chip technology, which is considered in Chapter 9. In this chapter, however, we focus on nonselective separation methods, which aim to take a complex protein mixture and fractionate it in such a manner that all the individual proteins, or at least a substantial subfraction, are available for further analysis. Such methods lie at the heart of proteomics and exploit very general properties of proteins, such as their mass or net charge.