What technique is commonly used for the purification of GFP?

Affinity chromatography is the technique most commonly used for the purification of GFP due to its high specificity and efficiency. This method capitalizes on the unique properties of GFP, particularly its ability to bind to specific ligands or tags attached to solid support materials such as columns. In the case of GFP, it is often fused to an affinity tag, like a histidine tag, which allows for its selective binding to nickel or cobalt ions immobilized on a chromatography resin.

During the purification process, a crude extract containing GFP is passed through the affinity column. The GFP binds to the resin while impurities are washed away. Later, a specific elution buffer is used to remove GFP from the resin by competing with the affinity interaction, leading to a concentrated and purified form of the protein.

While other techniques like gel filtration chromatography, size exclusion chromatography, and ion exchange chromatography can contribute to protein purification, they generally lack the specificity offered by affinity chromatography. These alternative methods may separate proteins based on size or charge rather than direct interactions, making them less suitable for efficient and clean purification of proteins like GFP that can be effectively purified using affinity tags.