What type of chromatography is often used to further purify GFP after affinity chromatography?

Size-exclusion chromatography is a technique commonly employed after affinity chromatography for the further purification of proteins like Green Fluorescent Protein (GFP). This method separates molecules based on their size, allowing larger proteins to elute from the column before smaller ones.

After the initial affinity chromatography step, which typically concentrates and purifies the target protein by exploiting the specific binding capabilities of a ligand, size-exclusion chromatography can remove any remaining impurities such as smaller proteins, peptides, and other contaminants. By doing this, it enables researchers to achieve a higher degree of purity for the GFP, making it suitable for various applications, including studies related to protein interactions, localization, and functionality.

The choice of size-exclusion chromatography is particularly beneficial because it does not require the use of additional chemical reagents that may interfere with subsequent analyses or applications of the protein. Thus, size-exclusion chromatography not only helps achieve high purity levels but also preserves the native state of the GFP throughout the purification process.