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The Strathprints institutional repository is a digital archive of University of Strathclyde research outputs.

Strathprints serves world leading Open Access research by the University of Strathclyde, including research by the Strathclyde Institute of Pharmacy and Biomedical Sciences (SIPBS), where research centres such as the Industrial Biotechnology Innovation Centre (IBioIC), the Cancer Research UK Formulation Unit, SeaBioTech and the Centre for Biophotonics are based.

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Bovine chymosin: a computational study of recognition and binding of bovine kappa-casein

Palmer, D. S. and Christensen, A. U. and Sørensen, J. and Celik, L. and Qvist, K. B. and Schiøtt, B. (2010) Bovine chymosin: a computational study of recognition and binding of bovine kappa-casein. Biochemistry, 49 (11). pp. 2563-2573.

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Abstract

Bovine chymosin is an aspartic protease that selectively cleaves the milk protein kappa-casein. The enzyme is widely used to promote milk clotting in cheese manufacturing. We have developed models of residues 97-112 of bovine kappa-casein complexed with bovine chymosin, using ligand docking, conformational search algorithms, and molecular dynamics simulations. In agreement with limited experimental evidence, the model suggests that the substrate binds in an extended conformation with charged residues on either side of the scissile bond playing an important role in stabilizing the binding pose. Lys111 and Lys112 are observed to bind to the N-terminal domain of chymosin displacing a conserved water molecule. A cluster of histidine and proline residues (His98-Pro99-His100-Pro101-His102) in kappa-casein binds to the C-terminal domain of the protein, where a neighboring conserved arginine residue (Arg97) is found to be important for stabilizing the binding pose. The catalytic site (including the catalytic water molecule) is stable in the starting conformation of the previously proposed general acid/base catalytic mechanism for 18 ns of molecular dynamics simulations.