Both PDI and PDIp can attack the native disulfide bonds in thermally-unfolded RNase and form stable disulfide-linked complexes

► Both PDI and PDIp can inactivate thermally-unfolded RNase that preserves native disulfide bonds. ► The N-terminal active site of PDIp plays a principal role in inactivating RNase. ► Stable disulfide-linked complexes are formed between PDI/PDIp and RNase. ► RNase can be released and reactivated from the PDI/PDIp-RNase complexes.