[Expression and characterization of protein disulfide isomerase-related protein A].

Protein disulfide isomerase-related protein A (PRPA) was highly expressed (about 34%) in Escherichia coli by inserting the whole PRPA cDNA into the vector pET23b. After expression, the purified protein was acquired through ammonium fractional precipitation and Bio-Rex 70 chromatography. PRPA shows low disulfide isomerase activity (only about 1/250 of that of hPDI), decreases the reactivation yield of denatured and reduced lysozyme either in redox and non-redox Hepes buffer or redox PBS buffer and facilitates the aggregation of denatured and reduced lysozyme. Fluorescence spectra of PRPA indicate that PRPA has more hydrophobic groups at surface than that of hPDI, and which can be used to explain why PRPA has anti-chaperone activity during the refolding of denatured and reduced lysozyme.