title: Interactions between protein disulphide isomerase and peptides.
abstract: There is growing evidence that protein disulphide isomerase (PDI) has a common chaperone function in the endoplasmic reticulum. To characterise this function, we investigated the interaction of purified PDI with radiolabelled model peptides, somatostatin and mastoparan, by cross-linking. The interaction between the peptides and PDI was specific, for it showed saturation and was abolished by denaturation of PDI. The interaction between a hydrophobic peptide without cysteine residues was much more sensitive to Triton X-100 than the interaction between PDI and a more hydrophilic peptide with or without cysteine residues. We therefore propose that hydrophobic interactions between protein disulphide isomerase and peptides play an important role in the binding process. The interaction between PDI and the bound peptide therefore is enhanced by the formation of mixed disulphide bonds.
authors.affiliation: Department of Biosciences, University of Kent, Canterbury, UK.
authors.forename: P
authors.initials: P
authors.lastname: Klappa
authors.forename: H C
authors.initials: HC
authors.lastname: Hawkins
authors.forename: R B
authors.initials: RB
authors.lastname: Freedman
mesh_terms: D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002417:Cattle; D003432:Cross-Linking Reagents; D003545:Cysteine / Q000737:chemistry; D066298:In Vitro Techniques; D036341:Intercellular Signaling Peptides and Proteins; D007535:Isomerases / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D011489:Protein Denaturation; D019704:Protein Disulfide-Isomerases; D017510:Protein Folding; D013004:Somatostatin / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D014862:Wasp Venoms / Q000737:chemistry / Q000378:metabolism
chemical_list: D003432:Cross-Linking Reagents; D036341:Intercellular Signaling Peptides and Proteins; D018832:Molecular Chaperones; D010455:Peptides; D014862:Wasp Venoms; D013004:Somatostatin; C037500:mastoparan; D007535:Isomerases; D019704:Protein Disulfide-Isomerases; D003545:Cysteine