Question

Gluten is a mixture of proteins abundant in wheat, barley, and rye. Although these grains are staples in the Western diet, almost 1 percent of Americans have celiac disease- a disorder of the intestines caused by an abnormal immune response after eating gluten. This immune response damages the fingerlike villi of the small intestine, which can lead to intestinal upset and malnourishment. Currently, the only treatment is to maintain a strict gluten- free diet. When you eat gluten, enzymes present in your stomach and intestines digest all but a few short peptides. How do enzymes accomplish this activity? a. The active site of an enzyme binds to a gluten protein and facilitates the hydrolysis reaction that breaks apart peptide bonds. b. An enzyme binds to the active site of a gluten protein and speeds up the condensation reaction that breaks apart peptide bonds. c. The active site of an enzyme binds to a gluten protein and reacts with it to break apart hydrogen bonds. d. An enzyme binds to the active site of a gluten protein and catalyzes the reactions that break apart hydrogen bonds.

Short answer

The correct mechanism by which enzymes break down gluten proteins in the stomach and intestines is through facilitating the hydrolysis reaction that breaks apart peptide bonds by binding to the active site of a gluten protein. Therefore, the correct short answer is: a. The active site of an enzyme binds to a gluten protein and facilitates the hydrolysis reaction that breaks apart peptide bonds.

Step-by-step solution

Understand the process of enzymes breaking down proteins

Enzymes are proteins that act as biological catalysts. They speed up chemical reactions in the body by providing an alternative reaction pathway with a lower activation energy. In the case of gluten digestion, enzymes break down gluten proteins into simpler molecules, primarily through hydrolysis reactions, which are reactions that involve the addition of water to break chemical bonds.

Analyze each option

Now, let's examine the options given: a. The active site of an enzyme binds to a gluten protein and facilitates the hydrolysis reaction that breaks apart peptide bonds. b. An enzyme binds to the active site of a gluten protein and speeds up the condensation reaction that breaks apart peptide bonds. c. The active site of an enzyme binds to a gluten protein and reacts with it to break apart hydrogen bonds. d. An enzyme binds to the active site of a gluten protein and catalyzes the reactions that break apart hydrogen bonds.

Determine the correct option

From our understanding of enzyme function, we can eliminate options c and d because they mention breaking apart hydrogen bonds instead of peptide bonds. Between options a and b, only option a mentions a hydrolysis reaction, which is the correct reaction for breaking apart peptide bonds in proteins. Option b refers to a condensation reaction, which is the opposite of hydrolysis and results in the formation of peptide bonds rather than breaking them.

Present the answer

The correct mechanism by which enzymes break down gluten proteins in the stomach and intestines is through facilitating the hydrolysis reaction that breaks apart peptide bonds by binding to the active site of a gluten protein. Therefore, the correct answer is: a. The active site of an enzyme binds to a gluten protein and facilitates the hydrolysis reaction that breaks apart peptide bonds.

Key concepts

Protein Digestion

Protein digestion is a crucial process that takes place in your stomach and intestines where enzymes dismantle complex proteins into simpler amino acids. These enzymes work like tiny, sophisticated machines, meticulously breaking down the intricate chains of proteins found in the food you eat, like the gluten in wheat. This is essential because only after proteins are broken down into amino acids, your body can absorb and utilize them to repair tissues, regulate bodily functions, and carry out numerous other activities critical to survival.

Imagine swallowing a pearl necklace; it would be far too large to wear as a ring. Protein digestion is like breaking apart the necklace into individual pearls so that they can be repurposed. This degradation of proteins is executed through a series of steps involving various enzymes, each specialized to cut at certain points, typically at the locations of peptide bonds, which hold the amino acid 'pearls' together.

Hydrolysis Reaction

The hydrolysis reaction is a fundamental chemical process that performs the essential function of breaking down compounds by adding water. When it comes to protein digestion, think of hydrolysis like using a drop of water to cut through a piece of string. In biochemical terms, the water molecule reacts with the peptide bonds holding amino acids together in the protein chain, resulting in the bonds breaking and the protein chain unraveling into individual amino acids or smaller chains of amino acids called peptides.

In the context of our body, this reaction doesn't just happen spontaneously; it requires a helper, which is where enzymes come into play. These biological catalysts lower the energy required to start the reaction, essentially enabling the water molecule to 'cut through' the peptide bond efficiently at body temperature, making the digestion process possible within a reasonable time frame.

Biological Catalysts

Biological catalysts, commonly known as enzymes, are special proteins that speed up biochemical reactions in living organisms without being consumed in the process. They function by creating a nurturing environment — termed the active site — for a specific chemical reaction to occur more easily and rapidly than it would on its own. Imagine you're trying to open a tightly sealed jar. The lid represents the high energy barrier that needs to be overcome for a reaction. Enzymes act like a rubber grip that provides a better hold on the lid, making it easier for you to twist it open.

Each enzyme is like a specialist that works only on one type of 'jar', meaning they are highly specific to their substrate, the substance with which they react. For protein digestion, the enzymes lock onto specific peptides and facilitate the hydrolysis reaction. The marvel of enzymatic activity is that it allows the same task — like breaking peptide bonds — to be carried out quickly and repeatedly, without the enzyme being used up.

Peptide Bonds

Peptide bonds are like the glue that holds the beads of a necklace together; they link amino acids to form proteins. These bonds are covalent, meaning they share electrons between atoms in a strong union, and they form when the amine group of one amino acid reacts with the carboxyl group of another, releasing a molecule of water in what is known as a dehydration synthesis reaction.

Given their sturdiness, peptide bonds do not readily break apart. That's where enzymes come in handy. They specifically target these bonds during protein digestion through hydrolysis, where they safely utilize water to break the bonds without damaging any of the 'beads' (amino acids). The broken peptide bonds result in shorter strings or individual amino acids, which the body can then absorb and repurpose to build new proteins and perform other vital functions.