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.
Kappeler
Stefan R
SR
Institute of Food Science, Swiss Federal Institute of Technology, CH-8092 Zurich, Switzerland.
van den Brink
Hans J M
HJ
Rahbek-Nielsen
Henrik
H
Farah
Zakaria
Z
Puhan
Zdenko
Z
Hansen
Egon Bech
EB
Johansen
Eric
E
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