Yes. The precursor of pepsin is called pepsinogen; it is produced by stomach cells and then activated by the HCl in the stomach. Pepsin works best at very low pH.... e.g. acid conditions of the stomach.
The small intestine has glands that produce neutralize the acid. Pepsin denatures at pH's of 5,0 or higher..... so effectively it is neutralized when the chyme enters the small intestine.
The pH level is not optimal for pepsin to work
Pepsin doesn't affect the pH but it is active in an acidic environment.
Lipase and amylase require an alkaline environment such as what is found in the duodenum of the small intestine. Pepsin functions in the acidic environment of the stomach.
Pepsin is a powerful protein digesting enzyme which is far too dangerous in its active form so it is released in an inactive pepsinogen form by the cell and activated only in the digestive tract where it is required to be active.
Pepsin degrades proteins so if it was active it would immediately begin digesting all the proteins in the cell. Therefore it is produced from a precursor known as a zymogen or proenzyme. Pepsin's proenzyme form is pepsinogen which is transformed to the activated pepsin protein.
Granted pepsin could kill a cell by hydrolyzing crucial proteins, it doesn't specifically destroy cells. It is a protease, a protein-digesting enzyme. There are two reasons why pepsin does not, under normal conditions, turn around and start digesting the cells of the host. Pepsin is only present in the stomach, where it is compartmentalized from the rest of the body. The mucous membrane protects the lining of the stomach so the stomach is not degraded by the enzymes or the strong hydrochloric acid. Secondly, pepsin is only active as an enzyme in very acidic environments like that of the stomach. Once the chyme of the stomach is dumped into the duodenum of the small intestine, the pH increases dramatically and the pepsin is denatured, no longer active to digest protein.
Because Pepsin is the active form of a protein manufactured in the stomach.
The carbohydrate molecule should not get fitted into the pepsin enzyme.
That is a proteolytic enzyme. Name of the enzyme is pepsin. It is secreted as inactive pepsinogen, which become active when it comes in contact with the hydrochloric acid, in the stomach.
pepsin is found in the stomach and the pH there is 2 while trypsin is found in the small intestine (duodenum and jejunum) and the pH there is 8-9. Thus, the optimum pH levels for pepsin and trypsin are 2 and 8-9 respectively.
Consider the stomach. The inactive form of the digestive enzyme pepsin is called pepsinogin. ( spelling may be wrong ) It takes the release of hydrochloric acid in the stomach to activate this pre-enzyme into pepsin, the active form. You would be digesting your own stomach tissue if pepsin was always active.