Enzyme questions?

Q1: When pepsin is secreted, it is in its inactive form called pepsinogen. Because it is inactive, it does not damage the cells that make it. When it is in the cavity of the stomach, pepsinogen is converted to its active form, pepsin, by losing a few dozen of its amino acids. The lining of the stomach is not affected by pepsin because pepsin acts only on proteins (mostly collagen, found in animal tissues), and the stomach is covered with mucus (a substance made from fats) that protects the protein-containing tissues — that is, unless you have a stomach ulcer.

Q2: Some bacteria are equipped with proton pumps such as the F1F0 ATPase, which bring about an increase in internal pH. Others have proton repair mechanisms involving chaperones, proteases, and heat shock proteins, which results in the protection of proteins or their degradation if damaged. DNA damaged as a consequence of a low internal pH can be repaired through the excision of errors or the restarting of stalled replication forks. Moreover, cell envelope alterations can protect cells by changing architecture, composition, stability, and activity. The production of alkali by their urease system increases the internal pH of the cell. Also metabolic properties can be altered.