This system produces such a large amount of your protein that it often kills the cell. A large amount of protein is produced before it kills the cell. Other expression systems use a thermolabile repressor, and induce by raising the temperature. This is achieved by purifying the protein so that your reaction contains no other proteins. Fractionation of Cells Cells lysed either by a number of methods.
Low speeds remove organelles.
Ultracentrifuge is used for supramolecular complexes. Small molecular complexes remain in solution and can be further fractionated by multiple chromatographic steps. The protein is eluted from the resin by adding a soluble form of the modified resin. If your protein doesn't interact with any ligand that can be readily immobilized on a resin, then you can engineer your protein to do so. A coding sequence for the following affinity 'tags' is fused in frame to one end of your gene.