Crystalline Human Urokinase: Some Properties

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Science  19 Feb 1965:
Vol. 147, Issue 3660, pp. 880-882
DOI: 10.1126/science.147.3660.880


Human urokinase, an enzyme which activates plasminogen, has been crystallized. Repeated recrystallization yielded preparations of maximum specific activity; such preparations revealed only one component when subjected to polyacrylamide gel disc electrophoresis. Studies with the ultracentrifuge demonstrated that urokinase undergoes a concentration-dependent reversible association at pH 6.8. When the partial specific volume of the enzyme is assumed to be 0.735 milliliters per gram at 10°C, Archibald measurements indicate the molecular weight of urokinase to be 53,000.