title: Hot-spot mapping of the interactions between chymosin and bovine κ-casein.
abstract: Chymosin is a commercially important enzyme in the manufacturing of cheese. Chymosin cleaves the milk protein κ-casein, which initiates the clotting process. Recently, it has been shown that camel chymosin has superior enzymatic properties toward cow's milk, compared to bovine chymosin. The two enzymes possess a high degree of homology. There are only minor differences in the binding cleft; hence, these must be important for binding the substrate. Models for the binding of a 16 amino acid fragment, consisting of the chymosin-sensitive region of bovine κ-casein (97-112), to both enzymes have previously been presented. Computational alanine scanning for mutating 39 residues in the substrate and the bovine enzyme are presented herein, and warm- (ΔΔG > 1 kcal/mol) and hot-spot (ΔΔG > 2 kcal/mol) residues in the bovine enzyme are identified. These residues are relevant for site-directed mutagenesis, with the aim of modifying the binding affinity and in turn affecting the catalytic efficacy of the enzyme.
authors.affiliation: The Center for Insoluble Protein Structures (inSPIN) and the Interdisciplinary Nanoscience Center (iNANO), Department of Chemistry, Aarhus University, Aarhus C, Denmark.
authors.forename: Jesper
authors.initials: J
authors.lastname: Sørensen
authors.forename: David S
authors.initials: DS
authors.lastname: Palmer
authors.forename: Birgit
authors.initials: B
authors.lastname: Schiøtt
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002162:Camelus; D002364:Caseins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D012085:Chymosin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D016415:Sequence Alignment
chemical_list: D002364:Caseins; D012085:Chymosin