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Protein Purification II: Affinity Tags

Scientists working with recombinant proteins expressed in Escherichia coli probably use at least one liquid chromatography technique to purify their protein of interest. But liquid chromatography frequently requires a considerable amount of optimization, and usually involves several different chromatographic steps to rid the sample of contaminants.1 The ideal solution would be to create a resin that is completely specific to the target protein, enabling one-step purification. Affinity chromatogr

Aileen Constans
Scientists working with recombinant proteins expressed in Escherichia coli probably use at least one liquid chromatography technique to purify their protein of interest. But liquid chromatography frequently requires a considerable amount of optimization, and usually involves several different chromatographic steps to rid the sample of contaminants.1 The ideal solution would be to create a resin that is completely specific to the target protein, enabling one-step purification.

Affinity chromatography theoretically does just that—a ligand that specifically interacts with the target protein is immobilized on a chromatography matrix; the target protein binds to the column, and unwanted proteins are eluted. In some cases, the affinity ligand is an antibody against the protein of interest; in others, the target protein is expressed from a plasmid that encodes for an "affinity tag" specific to a particular ligand.

This article discusses some of the affinity fusion systems available for recombinant proteins expressed in E....

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