On the effect of mutations in bovine or camel chymosin on the thermodynamics of binding κ‐caseins

Abstract

Bovine and camel chymosins are aspartic proteases that are used in dairy food manufacturing.Both enzymes catalyze proteolysis of a milk protein, j-casein, which helps to initiate milk coagulation. Surprisingly, camel chymosin shows a 70% higher clotting activity than bovine chymosin for bovine milk, while exhibiting only 20% of the unspecific proteolytic activity. By contrast, bovine chymosin is a poor coagulant for camel milk. Although both enzymes are marketed commercially, the disparity in their catalytic activity is not yet well understood at a molecular level, due in part to a lack of atomistic resolution data about the chymosin-j-casein complexes. Here, we report computational alanine scanning calculations of all four chymosin-j-casein complexes, allowing us to elucidate the influence that individual residues have on binding thermodynamics. Of the 12 sequence differences in the binding sites of bovine and camel chymosin, eight are shown to be particularly important for understanding differences in the binding thermodynamics (Asp112Glu, Lys221Val, Gln242Arg, Gln278Lys. Glu290Asp, His292Asn, Gln294Glu, and Lys295Leu. Residue

Can Recombinant Tree Shrew (Tupaia belangeri chinensis) Chymosin Coagulate Cow (Bos taurus) Milk?

“…Obtaining the rChn of the dromedary camel was the beginning of a new stage of research aimed at studying and understanding the mechanisms of the substrate specificity of neonatal gastric proteinases [9][10][11][12][13][14]. Moreover, the results of the study of C. dromedarius rChn continue to stimulate research aimed at the search and study of novel Chn species.…”