Effect of Bovine Plasmin on αs1 -B and κ-A Caseins

Abstract

Both αs1- and κ-caseins were incubated at 37 C in the presence of bovine plasmin (.28 mg/ml) prepared from fresh blood plasma. The electrophoretic pattern of κ-casein A was unchanged following 60-min incubation with plasmin. However, the electrophoretic band corresponding to αs1-casein B gradually disappeared during the initial 30-min incubation with plasmin. Proteolysis was accompanied by the formation of one polypeptide band with electrophoretic mobility slightly slower than αs1-casein B and several bands with faster electrophoretic mobilities. Two of the faster electrophoretic bands contained phosphorus. Estimates of molecular weights were 20,500, 12,300, and 10,300 daltons for three of these early degradation products of αs1-casein B by plasmin. © 1977, American Dairy Science Association. All rights reserved.