Characterization of recombinant camel chymosin reveals superior properties for the coagulation of bovine and camel milk.
Enzymatic milk coagulation for cheese manufacturing involves the cleavage of the scissile bond in kappa-casein by an aspartic acid protease. Bovine chymosin is the preferred enzyme, combining a strong clotting activity with a low general proteolytic activity. In the present study, we report expression and enzymatic properties of recombinant camel chymosin expressed in Aspergillus niger. Camel chymosin was shown to have different characteristics than bovine chymosin. Camel chymosin exhibits a 70% higher clotting activity for bovine milk and has only 20% of the unspecific protease activity for bovine chymosin. This results in a sevenfold higher ratio of clotting to general proteolytic activity. The enzyme is more thermostable than bovine chymosin. Kinetic analysis showed that half-saturation is achieved with less than 50% of the substrate required for bovine chymosin and turnover rates are lower. While raw camel milk cannot be clotted with bovine chymosin, a high clotting activity was found with camel chymosin.
Institute of Food Science, Swiss Federal Institute of Technology, CH-8092 Zurich, Switzerland.
Stefan R
SR
Kappeler
Hans J M
HJ
van den Brink
Henrik
H
Rahbek-Nielsen
Zakaria
Z
Farah
Zdenko
Z
Puhan
Egon Bech
EB
Hansen
Eric
E
Johansen
D000595:Amino Acid Sequence; D000818:Animals; D001234:Aspergillus niger / Q000235:genetics; D001483:Base Sequence; D002162:Camelus; D002364:Caseins / Q000737:chemistry; D002417:Cattle; D012085:Chymosin / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008892:Milk / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D013696:Temperature; D014162:Transfection
D002364:Caseins; D011994:Recombinant Proteins; D012085:Chymosin