On the Recovery of Genetically Engineered Proteins fromEscherichia coli

An overview of Escherichia coli (E. coli) as a host for the expression of useful eukaryotic proteins is presented. During the isolation of genetically engineered proteins from E. coli, one faces unique problems due to the precipitation of these proteins within cells. These problems include: 1) solubilization with strong denaturing agents, and 2) the removal of the denaturing agent under conditions optimal for protein folding. In addition there is the inherent inability of E. coli to perform various cotranslational and posttranslational events within its intra-cellular environment. Various approaches to solve some of the problems posed by the E. coli expression system for product recovery are critically evaluated and their usefulness and limitations are pinpointed. The impact of recombinant DNA technology on protein recovery from E. coli is discussed. Whether the intracellular expression in E. coli will continue to be the approach of choice for commercially useful proteins will depend upon our ability to find efficient and economical renaturation conditions as well as on the development of alternative expression systems.