Which buffer is primarily responsible for washing away contaminants?

The wash buffer's primary function is to remove contaminants from the sample during the purification process. This buffer is specifically designed to facilitate the removal of non-specifically bound proteins and other impurities without eluting the target protein itself—in this case, the Green Fluorescent Protein (GFP). By employing conditions that promote the desorption of unwanted materials, the wash buffer helps to enhance the purity of the isolated protein, ensuring that the desired GFP is subsequently collected with minimal contamination.

In comparison, the equilibration buffer is used to prepare the stationary phase of the purification column, stabilizing it and ensuring optimal conditions for binding. The binding buffer is critical for promoting the attachment of GFP to the column matrix during the initial stages of purification. Lastly, the elution buffer functions to release the bound protein from the column, allowing for its collection after it has been adequately purified from any contaminants. Each of these buffers plays a distinct role in the overall purification process, but only the wash buffer is specifically tasked with removing contaminants.