title: Dependence of the anti-chaperone activity of protein disulphide isomerase on its chaperone activity.
abstract: Protein disulphide isomerase (PDI) shows chaperone and anti-chaperone activities in assisting refolding of denatured and reduced lysozyme in redox Hepes buffer, but only chaperone activity in phosphate buffer and redox Hepes buffer containing 0.1 M NaCl. In non-redox Hepes buffer its anti-chaperone activity is very weak. PDI displays its anti-chaperone activity only for those substrates showing relatively low aggregation during refolding, and is strongly dependent on refolding conditions, of which ionic strength appears to be an important factor. The S-methylated PDI, fully active as a chaperone but devoid of isomerase activity, by itself shows only anti-chaperone activity, but reinforces rather than suppresses the chaperone activity of native PDI in the refolding of lysozyme. A fragment of PDI with the C-terminal peptide-binding sequence removed and devoid of chaperone activity does not show anti-chaperone activity in lysozyme refolding. It appears that the anti-chaperone activity of PDI is dependent on its chaperone activity.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing 100101, China.
authors.forename: J
authors.initials: J
authors.lastname: Song
authors.forename: H
authors.initials: H
authors.lastname: Quan
authors.forename: C
authors.initials: C
authors.lastname: Wang
mesh_terms: D000818:Animals; D002417:Cattle; D004789:Enzyme Activation; D019855:Ethylene Glycol / Q000494:pharmacology; D008099:Liver / Q000201:enzymology; D008745:Methylation; D018832:Molecular Chaperones / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000378:metabolism; D011489:Protein Denaturation / Q000187:drug effects; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism*; D017510:Protein Folding; D017384:Sequence Deletion / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D018832:Molecular Chaperones; D010446:Peptide Fragments; D012965:Sodium Chloride; D009113:Muramidase; D019704:Protein Disulfide-Isomerases; D019855:Ethylene Glycol