FIGURE 1 Column chromatography is performed in a glass or plastic tube containing one type of fractionating resin (matrix). The protein mixture is applied to the top of the column, and as buffer flows through, different proteins bind to the matrix according to the properties selected by the particular resin. These properties are typically the size or charge of the protein or the specific ligand to which the protein binds. Proteins are then dissociated from the matrix by eluting with a buffer that releases them at different times, and the proteins are collected in separate fractions.