Question

why epo enzyme is inactive​

Answer 1

All enzymes are secreted in inactive form to prevent any kind of reaction of the enzymes with other cells or tissues. Also, enzymes are secreted in the inactive form to regulate the proper fuction of the enzyme. It is released in inactive form, which goes to the target organ and then is activated by different means. And to prevent it's use when its not required.

Answer 2

The pancreas secretes zymogens partly to prevent the enzymes from digesting proteins in the cells in which they are synthesised. Enzymes like pepsin are created in the form of pepsinogen, an inactive zymogen. Fungi also secrete digestive enzymes into the environment as zymogens.