I regularly use bacterial expression systems for recombinant protein expression. Prior to large-scale production, I routinely trial small scale expression studies and the results of these small scale studies allow me to determine the best expression conditions to be used to scale up and purify large quantities of expressed protein. Given the number and types of expressed proteins our facility normally handles, I use a variety of affinity tags to purify the target proteins to a very high purity. I perform a wide range of different purification strategies and techniques (including batch affinity purification and FPLC column chromatography) to achieve the highest purity possible based on the biochemical properties of the target proteins.