Kininases and converting enzyme in human placenta.

Homogenized tissue of the human placenta is capable of inactivating bradykinin. Ultracentrifuging of the homogenate has shown that the highest activity cosediments with ribosomal fraction. Partial purification of the enzyme by filtration on Sephadex G-200 has been performed. Three protein peaks of kininase and converting activities were obtained. The optimum pH of kininase activity of placenta was determined. An attempt to determine molecular weight was made with the use of Sephadex G-200.Presented results indicate that the placental tissue of a normal woman produces enzymes with kininase activity and activity converting angiotensinase I to angiotensinase II, which may have significance in mechanisms of the local autoregulation of the blood flow.