EN
Over-expression of recombinant proteins in Escherichia coli, the most frequently used prokaryotic expression system, often results in the formation of intracellulary aggregated, insoluble folding intermediates. It is generally thought that protein aggregation is triggered by the failure of polypeptide intermediates to complete folding, leading to self-association. These aggregates are known as inclusion bodies or refractile bodies, since they appear upon microscopic observation as highly refractile areas. The formation of inclusion bodies often increases the yields of recombinant proteins and falicitates their isolation. The aggregated proteins are usually protected from proteases and do not harm host cells. Specific strategies are developed to produce bio-active proteins with the participation of inclusion bodies. These procedures include: 1) isolation and purification of inclusion bodies, 2) solubilization of the protein aggregates, and 3) renaturation of solubilized proteins involving formation of native disulphide bonds.