The bacterial periplasm is a compartment that allows formation of disulfide bonds. However, this compartment is characterized by an overall oxidizing milieu. Thus, wrong disulfide bonds are readily formed and poorly corrected by isomerization. The consequence is aggregate formation of misfolded and scrambled forms. Thus, strategies are being developed to engineer the periplasm into a compartment appropriate for oxidative folding.
Folding is facilitated by the secretion of folding enhancers and molecular chaperones.
Additionally, redox conditions of the periplasm are altered by modification of the culture medium. Upon these manipulations complex disulfide bridged proteins like tPA can be obtained in good yields in their native conformation. In a second approach the so far unexploited folding potential of the complete Escherichia coli cytosol is being explored. As we established a high through-put screening procedure for oxidative folding in the periplasm, the potential of total cell protein can now be tested for its effect on folding after secretion into the periplasmic space. Verbesserung der Ausbeute an nativ gefalteten Proteinen bei der Sekretion durch Zusatz von niedermolekularer Stoffen zum Kulturmedium.