Protein purification can be one of the most stressful lab activities. Working with proteins requires a substantial amount of properly folded, relatively pure protein, but getting to this stage is often much easier said than done. As reviewed in our Plasmids 101 series, proteins are overexpressed from a plasmid construct, most often in special E. coli strains designed for protein expression. Cultures are then lysed and the protein of interest is purified using an affinity tag. Additional tags may be used to improve protein stability and solubility.
Determining the best way to express one’s protein of interest can save a lot of time later.