Pepsin functions optimally in the human stomach at approximately pH 2. A student gradually increases the pH of a solution containing pepsin and its substrate from pH 2 to pH 8. Which of the following would most likely occur?

Core Concept

Enzymes have specific pH optima determined by the ionization states of amino acid side chains in the active site and throughout the protein. Raising the pH far from pepsin's optimum alters these charges, disrupting ionic bonds and hydrogen bonds that maintain the enzyme's tertiary structure and catalytic function.