A fast and simple method to eliminate Cpn60 from functional recombinant proteins produced by E. coli Arctic Express

• Recombinant proteins produced in Arctic Express E. coli are contaminated by Cpn60.
• A simple wash with subdenaturing urea concentration releases Cpn60.
• Hydrophobic interactions are involved between Cpn60 and recombinant proteins.
• After urea wash, an endoglucanase is fully active.
• The protocol was successfully tested on a viral protein.

A frequent problem of recombinant protein production is their insolubility. To address this issue, engineered Escherichiacoli strains like Arctic Express that produce an exogenous chaperone facilitating protein folding, have been designed. A drawback is the frequent contamination of the protein by chaperones. A simple method, using urea at a sub-denaturing concentration, allows unbinding of Cpn60 from expressed protein. This method was successfully used to purify 2 proteins, an enzyme and a viral protein. The enzyme was fully active. The nature of interaction forces between enzyme and Cpn60 was investigated. The method is likely applicable to purify other proteins.