An Endogenous Protease Activating Plasma Inactive Renin

1. The protease inhibitors Trasylol and soya-bean trypsin inhibitor prevented the activation of plasma inactive renin by acid.

2. N-Ethylmaleimide inhibited acid-activation to some extent but o-phenanthroline had no effect.

3. Acid-activation of the inactive renin in human plasma is mediated by a serine protease.