Which proteolytic enzymes are activated by acid hydrolysis of the proenzyme form?

Pepsin-pepsin is secreted in a proenzyme form in the stomach. unlike the majority of proenzymes, it is not activated by protease hydrolysis. instead, spontaneous acid hydrolysis at ph 2 or lower converts pepsinogen to pepsin. hydrochloric acid secreted by the stomach lining creates the acid environment. all the enzymes secreted by the pancreas are activated at the same time upon entrance into the duodenum. this is accomplished by trypsin hydrolysis of the inactive proenzymes trypsinogen, chymotrypsinogen, procarboxypeptidase, and proelastase. primer amounts of trypsin are derived from trypsinogen by the action of enteropeptidase secreted by the cells of the duodenum.