Summary
Three types of plasminogen activator could be distinguished in extracts from human
uterine tissue. The activators differed in thermostability or in mode of inhibition
by EACA.
All the extracts contained stable as well as labile activators. The saline extracts
were uniformly inhibited by increasing concentrations of EACA. Extracts made with
2 M ammonium thiocyanate were either uniformly inhibited by EACA or showed deflections
indicating contamination with an activator, which was inhibited in a biphasic manner.
It was possible to distinguish between: (1) An activator, abundantly present in the
tissue, which was uniformly inhibited and stable. (2) Another uniformly inhibited
activator, which was labile. (3) An activator, inhibited in a biphasic manner, similar
to urokinase, which was present in varying amounts in uteri with the endometrium in
the proliferative phase.
Gel filtration of the uterine extracts showed two major activity peaks corresponding
to particle sizes of 60,000 dalton and about 10,000 dalton.
Antiserum to purified plasminogen activator, prepared from porcine ovaries, inhibited
the activity of the human uterine extracts, but not the activities of human urokinase
or urine. Urokinase antiserum in a concentration completely inhibiting human urine
or urokinase, inhibited only 10% or less of the activities of human uterine extracts.
