MUTANT HUMAN PROTEIN DISULFIDE-ISOMERASE ASSISTS PROTEIN-FOLDING IN ACHAPERONE-LIKE FASHION

Human protein disulfide isomerase with an extra 10 amino acid residues of AEITRIDPAM at the N-terminal was expressed in E. coli as a soluble protein comprising 20% of total cell proteins, and was purified to ne ar homogeneity through one step of DEAE-Sephacel chromatography. The m utant enzyme, which had the same CD spectrum and comparable disulfide isomerase and thiol-protein oxidoreductase activities with that of the wild type human and bovine protein disulfide isomerases, also showed chaperone-like activity in stimulating the refolding of proteins conta ining no disulfide bond. The overall yield of the active product is ab out 20 mg l(-1) culture. (C) 1997 Elsevier Science B.V.