What is the purpose of hydrophobic interaction chromatography in this lab?

The purpose of hydrophobic interaction chromatography (HIC) in the lab is to separate hydrophobic proteins from others. This technique leverages the differences in hydrophobicity of proteins, which is a key characteristic that affects their interaction with the chromatography matrix. In HIC, proteins are typically applied to a column that has a hydrophobic stationary phase. Under high salt concentrations, the hydrophobic regions of the proteins are encouraged to interact with the hydrophobic ligands on the column, while more hydrophilic proteins are eluted earlier due to their weaker interactions. By gradually decreasing the salt concentration, the bound hydrophobic proteins can be selectively eluted based on their degree of hydrophobicity.

This method is particularly effective for purifying proteins like GFP, which has hydrophobic characteristics. The selective separation allows researchers to isolate the desired protein from others that may either be more hydrophilic or that have different hydrophobic properties, enhancing the purity and yield of the target protein. Other methods mentioned, such as isolating proteins based on size or measuring protein concentration, do not focus on the specific interactions related to hydrophobicity, which is the essence of what HIC is designed to achieve.