Skip to main content
. Author manuscript; available in PMC: 2010 Mar 2.
Published in final edited form as: Am J Physiol Gastrointest Liver Physiol. 2005 Dec 8;290(5):G894–G902. doi: 10.1152/ajpgi.00373.2005

Table 2. Effects of membrane-impermeable and -permeable protease inhibitors on zymogen activation.

Inhibitor in Cyt ZG ZG/Cyt ZG/Cyt/ATP Mic Mic/Cyt Mic/Cyt/ATP
Trypsin activity
−STI/PIC 0 101±12 100 0 110±10 100
+STI 0 114±18 111±4 0 107±4 91±2
+PIC 0 44±14* 57±10* 0 54±3* 58±8*
Chymotrypsin activity
−STI/PIC 0 39±8 100 0 67±10 100
+STI 0 42±5 119±10 0 69±13 97±4
+PIC 0 13±5* 41 ±12* 0 22±13* 44±6*

Values are means of %activity ± SE. For ZG data, maximal activity (100%) is set as ZG/Cyt/ATP using −STI/PIC Cyt. For Mic data, maximal activity (100%) is set as Mic/Cyt/ATP using −STI/PIC Cyt. In the absence or presence of membrane-impermeable protease inhibitor in the Cyt, no major difference in activity is seen, indicating that free enzyme is not contributing to activity. When PIC (containing membrane-permeant inhibitors) is present in Cyt, there is a significant reduction in activity (*P < 0.05). STI, soybean trypsin inhibitor; PIC, protease inhibitor cocktail.