Question

What would most likely happen to pepsin enzymes that traveled with the food from the stomach to the small intestines?

Answer 1

It will become inactive.

Explanation:

For an enzyme to work properly the environment has to have the right pH (acidity/basicity). They work within a certain range and have an optimum at which they work best. pH influences the folding of a protein and correct folding is essential for enzymes to function.

Pepsin enzymes have an optimum at `color(red)("pH 1.5-1.6")` (very acidic). The stomach provides an acidic environment in which these enzymes work best.

The pH changes drastically in the duodenum/small intestine (see image below) to a more neutral environment; `color(green)("pH 6-7")`. The pepsin enzymes will lose their enzymatic activity and are no longer functional. This is because the enzyme can't maintain its correct shape (folding) at higher pH.