Comparative electrophoretical studies of human and rabbit caseins

The chemical structure of a tetrasaccharide containing N-acetylglucosamine obtained from bovine colostrum kappa-casein

A tetrasaccharide consisting of D-galactose, N-acetylneuraminic acid, N-acetylglucosamine and N-acetylgalactosaminitol (1 : 1 : 1: 1) was obtained from bovine colostrum kappa-casein. It is the main carbohydrate portion of a caseinoglycopeptide formed by alkaline borohydride treatment. The carbohydrate sequence was analyzed by enzymatic and chemical methods and by mass spectrometry, and was shown to be N-acetylglucosaminyl-beta-1-3-galactosyl-beta-1-3[N-acetylneuraminyl-alpha-2-6- ]-N-acetylgalactosaminitol.

Structural aspects of the milk clotting process. Comparative features with the blood clotting process

The enzyme chymosin and its substrate, a casein fraction called k-casein, are involved in the milk clotting process. Recent data concerning the structure (peptide and sugar moieties) of various k-caseins and their role in casein micelles formation and stabilization are presented. The molecular events occurring during the primary phase of chymosin action on k-casein are discussed. Finally some structural features concerning more particularly the caseinoglycopeptides and the fibrinopeptides as well as the action of chymosin and thrombin involved in the milk and blood clotting processes are compared. Three examples of sequences of portions of k-caseins and fibrinogen presenting homology are presented.