Purification of bovine milk alkaline proteinase and comparison with purified bovine blood plasminogen or plasmin

Abstract

Summary -The bovine blood plasminogen (Plg) has been purified by affinity chromatography on Lysine-Sepharose. An electrophoresis pattern revealed sorne minor contaminant bands. The possibilities of contamination and activation of Pig have been examined; the Iikely causes of the heterogeneousness are: 1) an in vivo activation just before or during slaughter of the animais; 2) a partial activation during purification; 3) a self-activation or a self-hydrolyse which is a characteristic of proteinases or 4) a contamination of the chromatography column.The milk alkaline proteinase was purified by affinity chromatographies on Lysine-Sepharose and an immunoadsorbant (rabbit anti-bovine plasminogen serum) from whole casein and on enzymeenriched fraction. The purified fractions were partially heterogeneous and presented sorne minor components which are plasmin-chains. This sustains the assumption that self-activation or activation caused by traces of a whey activator in the whole casein occur. Blood and milk purified fractions were compared (electrophoresis, double-immunodiffusion, glycoprotein staining). This paper presents a nover method to purify the milk alkaline proteinase and to confirm the similarities between blood-and milk proteinase. milk alkaline proteinase 1 blood plasminogen or plasmin 1 purification 1 affinity chromategraphy 1 immunological reaction Résumé -Purification de la protéase alcaline du lait et comparaison avec la plasmine ou le plasminogène sanguins bovins purifiés. phy on Lysine-Sepharose will be described. Milk alkaline proteinase was also purified by affinity chromatography on immunoadsorbant using an antiplasminogen serum. Finally the products obtained by these purifications will be compared. Figure 1 depicts the experimental

Proteolysis of bovine β-casein by a plasmin-Sepharose conjugate

“…Alkaline proteinase or plasmin (Humbert and Alais, 1979;Grufferty and Fox, 1988), originating from bovine blood (Kaminogawa et al, 1972;Halpaap et al, 1977;Reimerdes et al, 1981;Humbert et al, 1990) is one of these milk enzymes. Many properties of plasmin have been clearly established.…”