Problem 4 What is a peptide bond and how i... [FREE SOLUTION]

Chapter 4: Problem 4

What is a peptide bond and how is it formed?

Short Answer

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Answer: A peptide bond is a covalent chemical bond that forms between two amino acids when the carboxyl group (COOH) of one amino acid reacts with the amino group (NH2) of another amino acid, resulting in the release of a water molecule (H2O). It is formed through a process that includes a nucleophilic attack, formation of a tetrahedral intermediate, loss of a water molecule, and finally the creation of the peptide bond. This bond is essential for constructing polypeptides and proteins, which play crucial roles in various biological processes in living organisms.

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Definition of a Peptide Bond

A peptide bond is a covalent chemical bond that forms between two amino acids when the carboxyl group (COOH) of one amino acid reacts with the amino group (NH2) of another amino acid, resulting in the release of a water molecule (H2O). This bond links amino acids together, creating a chain-like structure called a polypeptide or protein.

Amino Acid Structure

Before understanding the formation of a peptide bond, it's essential to know the structure of an amino acid. An amino acid is composed of a central carbon atom (called the alpha carbon), an amino group (NH2), a carboxyl group (COOH), a hydrogen atom, and a side chain (R group) that is unique for each amino acid.

Nucleophilic Attack

The first event in peptide bond formation is the nucleophilic attack, where the nitrogen from the amino group of one amino acid (acting as a nucleophile) attacks the carbon atom of the carboxyl group of another amino acid (acting as an electrophile).

Formation of Tetrahedral Intermediate

As a result of the nucleophilic attack, a tetrahedral intermediate is formed. The oxygen atom from the carboxyl group donates its lone pair of electrons to form a double bond with the central carbon atom, which leads to the expulsion of the hydroxyl group (OH) from the carboxyl group.

Loss of Water Molecule

The hydroxyl group (OH) from the carboxyl group of the first amino acid combines with a hydrogen atom (H) from the amino group of the second amino acid, forming a water molecule (H2O) that is released.

Formation of Peptide Bond

After the release of the water molecule, the nitrogen atom from the amino group of the second amino acid forms a covalent bond with the carbon atom of the carboxyl group from the first amino acid. This bond is called a peptide bond, and it links the two amino acids together, creating a dipeptide. In summary, a peptide bond is a covalent bond that forms between two amino acids through a condensation reaction, which results in the loss of a water molecule. This bond is crucial for constructing polypeptides and proteins, which are essential for various biological processes in living organisms.

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91影视

What is a peptide bond and how is it formed?

Short Answer

Step by step solution

Definition of a Peptide Bond

Amino Acid Structure

Nucleophilic Attack

Formation of Tetrahedral Intermediate

Loss of Water Molecule

Formation of Peptide Bond

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