Rennin and Pepsin

[nigel123]

The food in the stomach stimulates the gastric glands to secrete gastric juice into the stomach cavity. Gastric juice is made up of HCl and Rennin and Pepsin. These gastric enzymes are produced as inactive pepsinogen and prorennin which are converted by the HCl into active enzymes - pepsin and rennin.

1) Why are the 2 gastric enzymes secreted as inactive enzymes? why cant they be just secreted as active pepsin and rennin?

2) What is the function of Rennin?

[mith]

Well the enzymes are only supposed to act specifically in one location, the stomach. I'm guessing you don't want enzymes active when they are not in the stomach since the same stomach contents(enzymes and food) passes to the other parts of your alimentary canal.

[canalon]

You do not want them active after the stomach but they are secreted in the stomach, so it can't be the answer. IMHO it's rather that you don not want very active proteases in the cells that produces them, you want the enzyme to be active only in a cavity were your self is protected by mucus. So they are synthesized as an inactive form that can be handled safely by the producing cell and activated only where they are usefull and harmless.

For rennin, google is your friend. First website gives this:
http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/stomach/rennin.html
Chymosin, known also as rennin, is a proteolytic enzyme synthesized by chief cells in the stomach. Its role in digestion is to curdle or coagulate milk in the stomach, a process of considerable importance in the very young animal. If milk were not coagulated, it would rapidly flow through the stomach and miss the opportunity for initial digestion of its proteins.

HTH

Patrick