Multidimensional engineering of Chymosin for efficient cheese production by machine learning guided directed evolution
September 15-19, 2019
The global cheese market today exceeds $100B/year. Chymosin (a.k.a. rennin) is an aspartic endopeptidase produced by the stomach lining of new-born mammals. During cheese production chymosin is added to the milk where it cleaves the glycomacropeptide (GMP) from the surface of casein micelles to initiate milk coagulation. Current commercial recombinant chymosin enzymes derived from Bos taurus (cow) or Camelus dromedarius (camel) are limited in their proteolytic specificity leading to incomplete milk-to-cheese conversion. Increasing the chymosin specificity for GMP cleavage would significantly decrease the amount of milk needed for cheese production thereby reducing cost and decreasing environmental footprint of the dairy industry. Separate from milk coagulation, chymosin dependent release of N-terminal peptides from alphaS1 casein during cheese ripening leads to unwanted softening, accompanied with cheese loss during industrial processing such as slicing and shredding. Furthermore, chymosin dependent cleavage of the C-terminal end of beta casein contributes to unwanted bitterness of the cheese. Improvement of chymosin proteolytic specificity in both milk coagulation and cheese ripening is consequently of high commercial relevance.
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Christian Jäckel, Martin Lund, Hans van den Brink, Claes Gustafsson, and Sridhar Govindarajan, "Multidimensional engineering of Chymosin for efficient cheese production by machine learning guided directed evolution" in "Enzyme Engineering XXV", Huimin Zhao, University of Illinois at Urbana-Champaign, USA John Wong, Pfizer, USA Eds, ECI Symposium Series, (2019). https://dc.engconfintl.org/enzyme_xxv/110