Green tea catechins can bind and modify ERp57/PDIA3 activity

► Green tea catechins can bind ERp57 and modify its properties. ► The presence of a galloyl moiety is a key structural feature for the binding to ERp57. ► Galloylated catechins interact with ERp57 near the thioredoxin-like active sites. ► Galloylated catechins strongly inhibit ERp57 DNA binding capability.