Problem 62 - Chemistry The Central Science

Question

Write a chemical equation for the formation of methionyl-glycine from the constituent amino acids.

Step-by-Step Solution

Answer

The chemical equation for the formation of methionyl-glycine from its constituent amino acids methionine and glycine is: \( C5H11NO2S (Methionine) + C2H5NO2 (Glycine) \rightarrow C7H14N2O3S (Methionyl-Glycine) + H2O \)

Step 1: 1. Write the chemical formulas of the amino acids involved

First, we need to write down the chemical formulas for methionine and glycine: Methionine: C5H11NO2S Glycine: C2H5NO2

Step 2: 2. Formation of the dipeptide bond

The peptide bond formation involves a condensation reaction between the carboxyl group of one amino acid and the amino group of another amino acid, leading to the creation of the dipeptide bond and a water molecule.

Step 3: 3. Write the dipeptide bond formation equation

Write the chemical equation for the formation of methionyl-glycine: \( C5H11NO2S (Methionine) + C2H5NO2 (Glycine) \rightarrow C7H14N2O3S (Methionyl-Glycine) + H2O \)

Step 4: 4. Balanced chemical equation

The given equation is already balanced because there's an equal number of atoms of each element on both sides of the equation: C5H11NO2S + C2H5NO2 → C7H14N2O3S + H2O

Key Concepts

Amino Acids

Amino acids are the building blocks of proteins. They play a crucial role in the formation of peptides and proteins, which are essential for various biological functions. An amino acid consists of:

• An amino group (-NH2)
• A carboxyl group (-COOH)
• A unique side chain (R group) that determines its properties

Methionine (\( C_5H_{11}NO_2S \) ) and glycine (\( C_2H_5NO_2 \) ) are examples of amino acids. Methionine has a sulfur atom in its side chain, while glycine is the simplest amino acid with a hydrogen atom as its R group. These unique structures of methionine and glycine allow them to participate in peptide bond formation, which is the cornerstone of building larger protein structures.
Understanding amino acids helps us comprehend the chemical processes that create essential biomolecules.

Condensation Reaction

The condensation reaction is the process that connects amino acids to form peptide bonds. This reaction occurs when the carboxyl group of one amino acid reacts with the amino group of another, releasing a water molecule (\( H_2O \) ).

• First, the carboxyl group (-COOH) of one amino acid loses an -OH group.
• Simultaneously, the amino group (-NH2) of another amino acid loses a hydrogen atom.
• The release of \( H_2O \) binds both amino acids together, forming a peptide bond.

Such reactions are fundamental in biology as they form the peptide links between amino acids to create dipeptides, tripeptides, and eventually complex proteins. This process underlines the transformation of simple building blocks into intricate structures necessary for life.

Chemical Equation

Writing a chemical equation allows one to represent the chemical change occurring during a reaction. For the formation of methionyl-glycine from methionine and glycine, we use their chemical formulas:

• Methionine: \( C_5H_{11}NO_2S \)
• Glycine: \( C_2H_5NO_2 \)

The chemical equation is:\[ C_5H_{11}NO_2S + C_2H_5NO_2 \rightarrow C_7H_{14}N_2O_3S + H_2O \]This reaction describes the combination of methionine and glycine to produce methionyl-glycine and a molecule of water. Balancing chemical equations is crucial because it ensures that the quantity of each element remains constant, reflecting the conservation of mass. This balanced equation depicts a smooth transition from reactants to products.

Dipeptide

A dipeptide is formed by two amino acids linked by a single peptide bond. In this example, methionyl-glycine is the dipeptide resulting from the condensation reaction between methionine and glycine. Guided by the reaction:

• The amino group of methionine bonds with the carboxyl group of glycine.
• The result is a chain: methionyl-glycine.

Dipeptides are simple structures yet pivotal in the study of larger peptides and proteins. They help us understand how protein chains are built and how varied sequences of amino acids contribute to diverse functions and shapes of proteins in living organisms. By studying dipeptides, we gain insight into the linear progression of amino acid bonding that characterizes protein synthesis.