The digestion of proteins begins in the stomach of the gastrointestinal tract. This crucial process occurs regularly whenever food is consumed and requires specialized enzymes that act on specific compounds. The enzyme pepsin is responsible for protein digestion. Pepsin, along with hydrochloric acid, is secreted by the stomach. Once proteins reach the stomach, these enzymes break them down into smaller chains of amino acids. These smaller chains then move into the small intestine, where they are further broken down into individual amino acids.