Hot-spot mapping of the interactions between chymosin and bovine κ-casein

Jesper Sørensen, David Palmer, Birgit Schiøtt

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9 Citations (Scopus)

Abstract

Chymosin is a commercially important enzyme in the manufacturing of cheese. Chymosin cleaves the milk protein -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 kappa-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.
Original languageEnglish
Pages (from-to)7949-7959
Number of pages11
JournalJournal of Agricultural and Food Chemistry
Volume61
Issue number33
DOIs
Publication statusPublished - 8 Jul 2013

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Keywords

  • chymosin
  • casein
  • binding free energy
  • cheese manufacturing
  • enzyme
  • alanine scanning
  • mutagenesis
  • protein-ligand

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