What is the effect of sodium hydroxide on the action of pepsinogen?

Answer 1

Sodium Hydroxide and Pepsin

Pepsinogen is an inactive form of the enzyme pepsin. Pepsin is a protease, meaning a hydrolytic enzyme, one that breaks down its substrate. In the stomach, pepsin breaks down proteins to smaller polypeptides and amino acids. The environment in the stomach is very acidic due to hydrochloric acid (HCl), with a pH of 1.5 - 2. The HCl will clip off portions of the pepsinogen, thereby activating the pepsin. Pepsin will only be active in these very acidic environments. Sodium hydroxide (NaOH) will neutralize the acid and therfore raise the pH of the stomach. We can see this in the following chemical equation.

HCl + NaOH → H2O + NaCl

When a base is added to the very acidic chyme in the stomach, the pH suddenly increases. Subsequently, the pepsinogen cannot be activated into pepsin and any pepsin is denatured because it is out of is pH range. If sodium hydroxide is introduced in the stomach, no proteins will be hydrolyzed.

In the digestive process, pepsinogen is inactivated when the chyme is dumped into the small intestine. Because the small intestine is not protected like the stomach, secretin stimulates the pancreas to secrete bicarbonate ions. Bicarb ions neutralize the acidic solution to about 7-8. The presence of the bicarb ions stops the protein-digesting process.

Answer 2

Hydrochloric acid changes pepsinogen to active pepsin