DISTRIBUTION OF PLASMINOGEN-ACTIVATOR FORMS IN FRACTIONS OF GOAT MILK

Distribution of plasminogen activator forms in fractions of goat milk was examined. Raw milk was centrifuged to separate skim milk, cream, a nd a somatic cell pellet. Somatic cell extracts were obtained by sonic ation. Skim milk was centrifuged to separate milk serum and casein mic elles. Activity of plasminogen activator was detected in casein, serum fractions, and in association with somatic cells. Plasminogen activat or forms in milk casein had approximate molecular weights of 75,000, 5 0,000, and 30,000. The predominant forms of plasminogen activator in m ilk serum and in association with milk somatic cells had molecular wei ghts of 30,000 and 50,000. Based on fibrin dependency and inhibition o f activity in the presence of amiloride, the forms at 30,000 and 50,00 0 represent urokinase-plasminogen activator, and the form at 75,000 re presents tissue-plasminogen activator.