The analysis of proteins, whether on a small scale 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.
Whether protein separation is selective, partially selective or nonselective, it is important to remember that the underlying principle is always the exploitation of physical and chemical differences between proteins which cause them to behave differently in particular environments. These physical and chemical differences are determined by the number, type and order of amino acids in the protein, and by any PTMs that have taken place.
Two predominant methods to separate proteins are 2D gel electrophoresis and chromography techniques.