Question

Peptide decomposition is one of the key processes of digestion, where a peptide bond is broken into an acid group and an amine group. We can describe this reaction as follows: \(\text { Peptide }(a q)+\mathrm{H}_{2} \mathrm{O}(t) \rightleftharpoons \text { acid group }(a q)+\text { amine group }(a q)\)

Short answer

In the peptide decomposition reaction, the reactants are the peptide (aq) and water (H₂O), which leads to the formation of acid group (aq) and amine group (aq) as the products. The peptide bond is broken due to the interaction with water, as water donates a hydrogen ion (H⁺) to the amine group and a hydroxide ion (OH⁻) to the acid group. The reaction is reversible, indicating that it can proceed in both directions, from reactants to products and vice versa.

Step-by-step solution

Identify the reactants and products of the reaction

In the peptide decomposition reaction, we have the following reactants and products: Reactants: 1. Peptide (aq) 2. Water (H₂O) Products: 1. Acid group (aq) 2. Amine group (aq) Now that we have identified the reactants and products let's proceed with the decomposition process.

Understand the role of water in the reaction

In this reaction, water acts as a reactant, which helps in breaking the peptide bond. The water molecule donates a hydrogen ion (H⁺) to the amine group and a hydroxide ion (OH⁻) to the acid group. This leads to the formation of an acid group and an amine group as a result of the decomposition process.

Breaking of peptide bond

The peptide bond is broken when water interacts with the peptide. The breakdown can be depicted as the following: 1. Peptide (aq) + H₂O → Peptide with a broken bond + H⁺ + OH⁻ 2. Peptide with a broken bond + H⁺ → Acid group (aq) 3. Peptide with a broken bond + OH⁻ → Amine group (aq) So, the overall reaction can be represented as: Peptide (aq) + H₂O → Acid group (aq) + Amine group (aq)

Reversible reaction

The given reaction is a reversible reaction, as indicated by the double arrows (\(\rightleftharpoons\)). This means that the reaction can proceed in both directions from reactants to products and from products to reactants. In the context of this exercise, it implies that peptide decomposition can take place, as well as peptide synthesis (amine and acid groups combining to form a peptide). In summary, the peptide decomposition reaction can be analyzed in the following steps: 1. Identifying the reactants and products 2. Understanding the role of water in the reaction 3. Breaking the peptide bond to form acid and amine groups 4. Considering the reversible nature of the reaction

Key concepts

Peptide Bond

The peptide bond is a covalent chemical bond linking two consecutive amino acids from C1 (carbon number one) of one amino acid and N2 (nitrogen number two) of another. Formed through a dehydration synthesis reaction (also known as a condensation reaction), this bond is a key player in shaping the structure and function of proteins.

During the formation of a peptide bond, a water molecule is released as the carboxyl group of one amino acid reacts with the amine group of another. In the context of digestion, enzymes called proteases catalyze the reverse process where water is used to break the bond in hydrolysis. This reaction cleaves the peptide bond, resulting in the formation of separate amino acids or smaller strings of amino acids known as peptides.

Digestion Process

The digestion process refers to the breakdown of food into smaller, absorbable components by enzymes. In the case of proteins, the goal is to break down complex chains of amino acids into individual amino acids or small peptides that can be absorbed into the bloodstream.

In the human digestive system, this process begins in the stomach with enzymes like pepsin and continues in the small intestine using enzymes such as trypsin and chymotrypsin. These enzymes are highly specific to the peptide bonds they target, ensuring that proteins are methodically broken down into their building blocks through a series of hydrolytic reactions.

Chemical Reaction

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. These processes are characterized by changes in the chemical composition through breaking and forming of bonds, which involve the rearrangement of atoms.

In particular, peptide decomposition is a type of hydrolysis reaction, where water interacts with a peptide to break it into an acid group and an amine group. It’s crucial to recognize the role of water as a reactant in this reaction; it provides the components necessary to successfully break the peptide bond.

Reversible Reaction

A reversible reaction is one that can proceed in both the forward and reverse directions. The concept of reversibility is important in biochemistry, where many reactions are under dynamic equilibrium, meaning that the rate of the forward reaction is equal to the rate of the reverse reaction.

Peptide synthesis and decomposition are classic examples of reversible reactions. Although in the human body, the synthesis (anabolism) typically occurs in cells whilst decomposition (catabolism) occurs during digestion, in a laboratory setting, we can observe these reactions happening in both directions under different conditions.

Biochemistry

Biochemistry is the branch of science concerned with the chemical processes and substances that occur within living organisms. It combines biology and chemistry to explore the molecular mechanisms that underlie various biological processes.

Understanding peptide bonds and the digestion process are fundamental concepts in biochemistry. These processes not only unravel how energy and nutrients are derived from food but also provide insight into the vital functions proteins serve in the body, such as enzyme catalysis, cellular communication, and the immune response.