Distribution of Urokinase Among the Common Mammals

¹ From the Carter Physiology Laboratory and Department of Biochemistry, University of Texas Medical Branch, Galveston, Texas

Urokinase, a principle capable of activating profibrinolysin to fibrinolysin, has been found in the urine of the cat, rat, cow, rabbit, man, dog and hamster. Soluble concentrates of this activator were prepared by precipitation of urine with equal volumes of cold acetone, suspension of the precipitate in borate buffer and sequential dialysis of the suspension against borate buffer (ph 9.2), distilled water and phosphate buffer (ph 7.25). The ability of the urokinase concentrates from the urine of a given species to activate the profibrinolysin of its own and various other species was measured in a two-stage assay system which is described. The activation of profibrinolysin by urokinase was limited by definite species specificities and did not appear to involve the intermediation of a plasma prokinase.