Single-step recovery and solid-phase refolding of inclusion body proteins using a polycationic purification tag.

A strategy for purification of inclusion body-forming proteins is described, in which the positively charged domain Z(basic) is used as a fusion partner for capture of denatured proteins on a cation exchange column. It is shown that the purification tag is selective under denaturing conditions. Furthermore, the new strategy for purification of proteins from inclusion bodies is compared with the commonly used method for purification of His(6)-tagged inclusion body proteins. Finally, the simple and effective means of target protein capture provided by the Z(basic) tag is further successfully explored for solid-phase refolding. This procedure has the inherited advantage of combining purification and refolding in one step and offers the advantage of eluting the concentrated product in a suitable buffer.