The role of protein disulfide isomerase (PDI) in oxidative folding

Protein Disulfide Isomerase is a highly evolved oxidoreductase enzyme that has the capability of oxidizing, reducing, and isomerizing disulfides in substrate. PDI is organized into several domains denoted a, b, b\u27, a\u27 and c. These domains are believed to have different functions but all must be present for full PDI activity. In this manuscript we recorded the ability of PDI b\u27 to catalyze oxidative folding in fully reduced RNase A. We also examined competition between thiol-disulfide shuffling and conformational folding by PDI. This competition creates a rough effect of a highly efficient enzyme in two different substrates: RNase A and Alpha-lactalbumin. Conformational structure is removed from each exposing the disulfides which are attacked by PDI preventing the substrates from folding as the concentration of PDI is increased