title: Effect of protein disulfide isomerase on the rate-determining steps of the folding of bovine pancreatic ribonuclease A.
abstract: The effects of protein disulfide isomerase (PDI) on the four structured des species that accumulate in the rate-determining steps of ribonuclease A folding were investigated at pH 8.0 and 15 degrees C. The results indicate that PDI catalyzes the conversion of the kinetically trapped intermediates, des-[26-84] and des-[58-110], by reshuffling them into the on-pathway intermediate, des-[40-95], and the formation of native protein, by acting as both a chaperone and an oxidase on this on-pathway intermediate. These results provide the first strong evidence for the mechanism of PDI in the rate-determining steps of the oxidative folding pathways of ribonuclease A. Our approach, using PDI and blocked PDI, combined with the fast-blocking 2-aminoethyl methanethiosulfonate method, may be generally applicable to the clarification of the effect of PDI on folding intermediates.
authors.affiliation: Baker Laboratory of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA.
authors.forename: Hang-Cheol
authors.initials: HC
authors.lastname: Shin
authors.forename: Myeong-Cheol
authors.initials: MC
authors.lastname: Song
authors.forename: Harold A
authors.initials: HA
authors.lastname: Scheraga
mesh_terms: D000818:Animals; D002417:Cattle; D004229:Dithiothreitol; D019704:Protein Disulfide-Isomerases / Q000378:metabolism*; D017510:Protein Folding; D012259:Ribonuclease, Pancreatic / Q000096:biosynthesis*
chemical_list: D012259:Ribonuclease, Pancreatic; D019704:Protein Disulfide-Isomerases; D004229:Dithiothreitol