I am doing ACE activity assays in pancreas and lungs tissue homogenates by using specific fluoroscent substrate (Mca-RPPGFSAFK(Dnp)-OH) and specific inhibitor (captopril). As compared to lungs, in pancreas slight or no inhibition of the fluorescence by captopril. This means, apart from ACE other enzymes are also acting on the fluorescent substrate and that might be the reason for less inhibition by captopril. So the main problem with pancreas is non-specific hydrolysis of the fluorescent substrate in the pancreas.

How should I get rid of the non-specific hydrolysis in pancreas homogenates