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

Abstract

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 hetero-geneousness 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 enzyme-enriched 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 chromate-graphy 1 immunological reaction Résumé-Purification de la protéase alcaline du lait et comparaison avec la plasmine ou le plasminogène sanguins bovins purifiés. Le plasminogène du sang bovin a été purifié par chro-matographie d'affinité sur Lysine-Sepharose. Il présente une bande majeure et des bandes mi-neures en électrophorèse et un arc contaminant en double immunodiffusion. Les possibilités de contamination ou d'activation du plasminogène sont examinées; ces causes d'hétérogénéité se-raient: