Biochimie de la coagulation enzymatique du lait

Abstract

The primary enzymatic phase of chymosin (or rennin, EC. 3, 4, 4, 3) on cow casein is confined to the κ-casein fraction; the protective colloid is so destroyed. The digestion yields a very soluble “caseino-peptide” having special properties; it forms the C-terminal moiety of the κ-casein molecule containing all the sugars; the insoluble moiety “para-κ-casein” is linked to the caseino-peptide by a peptidic bond (Phe-Met) ; it is probably the unique linkage splitted off during this reaction. There is a relationship between the limited proteolysis of κ-casein and the clotting time of milk.

The limited proteolysis occurs also with pepsin. Some fungal proteases having a low proteolytic activity on casein can be used as chymosin substitutes for milk coagulation.