Trypsin activation of human and cat prorenin: a comparative study.

Prorenin can be converted to renin by limited proteolysis with trypsin. In the current study we compared conditions for activation of human renal and ovarian prorenin and cat renal prorenin with either liquid-phase trypsin or trypsin bound to sepharose (solid phase). Higher concentrations of trypsin were required to activate cat prorenin than human prorenin. Human prorenin was destroyed by high concentrations of trypsin, while cat prorenin was not destroyed by up to 2 mg/mL solid-phase trypsin. For both human and cat prorenin, addition of the competitive serine protease inhibitor benzamidine--HCl increased the concentration of trypsin needed to activate prorenin, resulting in slightly higher levels of human prorenin but lower levels of cat prorenin. For human samples, activation with solid-phase trypsin resulted in slightly higher estimates of prorenin than liquid-phase trypsin. These results demonstrate species differences in the susceptibility of prorenin to trypsin cleavage. Cat prorenin requires more trypsin to be activated and is less susceptible to destruction than human prorenin.