OXIDATIVE REFOLDING OF BOVINE PANCREATIC RNASE-A AND RNASE-B PROMOTEDBY ASN-GLYCANS

It was previously revealed [Yamaguchi, H. and Uchida, M. (1996) J. Bio chem. 120, 474-477] that both intra-and extramolecular high-mannose ty pe Asn-glycans promote the renaturation of reductively denatured bovin e pancreatic RNases A and B under oxidation conditions. To characteriz e the conformational changes of the polypeptides during the renaturati on promoted by the intramolecular Asn-glycans, RNase B was compared wi th its nonglycosylated form, RNase A, as to the features of the regene ration from their reductively denatured species under Cu2+-catalyzed o xidation conditions. The refolding intermediates of RNase B, as compar ed with those of RNase A, seemed to contain much less impaired disulfi de linkages. In agreement with this finding, the proper refolding of R Nase B was much faster than that of RNase A, as revealed by the intrin sic fluorescence and 1-anilino-8-naphthalenesulfonate binding of the r efolding intermediates. Such a promoting effect was also observed for extramolecular Asn-glycans of the complex as well as of the high-manno se type. In contrast, common mono-, oligo-, and polysaccharides, but n ot yeast mannan, exhibited much lower stimulatory effects on the oxida tive refolding of RNase A.