Which enzyme is responsible for breaking down proteins in the stomach?

Pepsin is the enzyme responsible for breaking down proteins in the stomach. It is produced in an inactive form called pepsinogen, which is secreted by the gastric glands in the stomach. When pepsinogen encounters the acidic environment of the stomach, it is activated into pepsin. This enzyme specifically cleaves the peptide bonds in proteins, facilitating their breakdown into smaller peptides, which is crucial for digestion.

The function of pepsin is essential in the digestive process, as it allows proteins ingested in food to be processed properly so that they can be absorbed later in the small intestine. The presence of hydrochloric acid in the stomach not only activates pepsinogen but also creates the ideal acidic environment for pepsin to function effectively.

In contrast, amylase is an enzyme that breaks down carbohydrates, lactase is involved in the digestion of lactose (milk sugar), and trypsin is an enzyme that functions in the small intestine to further digest proteins that have been partially broken down by pepsin. Thus, pepsin stands out as the primary enzyme for protein digestion specifically in the stomach.