Characterization of recombinant camel chymosin reveals superior properties for the coagulation of bovine and camel milk

Stefan R. Kappeler, Hans (J.) M. van den Brink, Henrik Rahbek-Nielsen, Zakaria Farah, Zdenko Puhan, Egon Bech Hansen, Eric Johansen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Enzymatic milk coagulation for cheese manufacturing involves the cleavage of the scissile bond in κ-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.
Keyword: Camelus dromedarius,Milk clotting enzyme,Heterologous gene expression,Cheese,Camel chymosin,Aspergillus niger
Original languageEnglish
JournalBiochemical and Biophysical Research Communications
Volume342
Issue number2
Pages (from-to)647-654
ISSN0006-291X
DOIs
Publication statusPublished - 2006
Externally publishedYes

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