Proposed mechanism for rescue of recombinant protein solubility.

We hypothesize that up to 80% of the seemingly insoluble recombinant proteins are in a partially folded state and reside in the E. coli cytosol. If lysed in a non-ideal buffer, the proteins unfold, resulting in aggregates of insoluble protein. When the sample is centrifuged to separate the soluble fraction, the protein aggregates are present in the insoluble cell pellet. If the additives are present during cell lysis, they can either stabilize the proteins from partially unfolding, preventing protein-protein interactions, or aid as chemical chaperones, leading to the properly folded and non-aggregated state. When centrifuged there are minimal protein aggregates and the recombinant protein remains in the soluble fraction.