Enzymes are generally made up of protein molecules and work at an optimum pH and temperature. This is because at change in pH and temperature leads to denaturation of proteins that cause change in active site of enzyme.
For trypsin, optimum pH is slightly basic as pH (7.5). So, trypsin would become non-functional at acidic pH due to denaturation and loss of active site.
Trypsin is a pancreatic enzyme that works at small intestine as pH of small intestine is slightly basic.Thus, if the trypsin was secreted in stomach instead of pancreas, it would be non-functional as stomach has acidic pH due to stomach acid.
