Figure 7.

Proposed mechanism of isomerization by DsbC. For clarity, only a monomer of DsbC is shown. Reduced active DsbC recognizes misoxidized substrate (1) and forms a mixed-disulfide bonded complex. This complex (2) can be resolved by the reduction of the disulfide bond in the substrate, resulting in the oxidation of DsbC (3). A secondary cycle of reduction is necessary for the substrate to be fully reduced (4), allowing DsbA to reoxidize the substrate (5). Alternatively, the disulfide bonds in the complex can be shuffled (6) by the isomerase action of DsbC, resulting in native disulfide bonded substrate and reduced DsbC (7).