title: Functional implication of disulfide bond, Cys250 -Cys283, in bovine chymosin.
abstract: The reduction, carboxymethylation and mercuration of disulfide bond, Cys250-Cys283, located on the surface of bovine chymosin molecule resulted in the loss of about 25% of enzyme activity, suggesting that Cys250-Cys283 is not intimately involved in catalytic mechanism. Cys250 and Cys283 were substituted with Asp. and Ser. by site- directed mutagenesis of the structural gene coding for bovine prochymosin B. All three mutants (C250D/C283S, C250D, C283S) failed to be activated to chymosin in acid, indicating that Cys250-Cys283 might have some contribution to the correct refolding of the unfolded prochymosin.
authors.affiliation: Institute of Microbiology, Chinese Academy of Sciences, Beijing.
authors.forename: K
authors.initials: K
authors.lastname: Huang
authors.forename: Z
authors.initials: Z
authors.lastname: Zhang
authors.forename: N
authors.initials: N
authors.lastname: Liu
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: G
authors.initials: G
authors.lastname: Zhang
authors.forename: K
authors.initials: K
authors.lastname: Yang
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002384:Catalysis; D002417:Cattle; D012085:Chymosin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003545:Cysteine / Q000737:chemistry* / Q000378:metabolism; D004247:DNA / Q000737:chemistry; D004220:Disulfides / Q000378:metabolism*; D005796:Genes; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D013329:Structure-Activity Relationship
chemical_list: D004220:Disulfides; D004247:DNA; D012085:Chymosin; D003545:Cysteine