The key difference between amide and peptide bond is that an amide bond forms between a hydroxyl group and an amino group of two molecules whereas a peptide bond forms between two amino acid molecules during the formation of a peptide chain.
Amide bonds and peptide bonds are biochemical bonds that form between a carbon atom and a nitrogen atom of two separate molecules. Usually, these bonds form between two amino acid molecules.
CONTENTS
1. Overview and Key Difference
2. What are Amide Bonds
3. What are Peptide Bonds
4. Side by Side Comparison – Amide vs Peptide Bond in Tabular Form
5. Summary
What are Amide Bonds?
Amide bonds are a type of covalent bond that forms an amide as the final product. There are three major types of amides as carboxamides, sulfonamides, and phosphoramides. However, the simplest amides are derivatives of ammonia.
Figure 01: Different Amide Bonds
Amides are generally ranked as very weak bases when compared to amines. Therefore, these substances do not show acid-base properties in water. A peptide bond is a type of amide bond. Here, the amide bond forms when the carboxylic acid group of one amino acid reacts with the amine group of another amino acid. A covalent bond forms by removing a water molecule. Therefore, it is a condensation reaction.
What are Peptide Bonds?
A peptide bond is a type of covalent bond that forms between two amino acids. A peptide bond forms between a carbon atom of one amino acid and the nitrogen atom of the amino acid that occurs with the removal of a water molecule. When considering the basic structure of amino acid, it consists of a central carbon atom attached to a carboxylic group, amino group, hydrogen atom and an alkyl group. Generally, amino acids differ from each other according to the structure of the alkyl group.
During the formation of a peptide bond, a condensation reaction occurs between two amino acids. Here, the carboxylic acid of one amino acid reacts with the amine group of another amino acid, releasing a water molecule. The –OH group of the carboxylic acid group forms a water molecule, combining with a hydrogen from amine group.
We can abbreviate the peptide bond as –CONH- bond because the bond that forms involves these four atoms. When two amino acids bind to each other through one peptide bond, the final product is a dipeptide. However, if several amino acids bind with each other, then an oligopeptide forms. If a high number of amino acids binds with each other through peptide bonds, the complex molecule is a polypeptide.
A peptide bond can undergo hydrolysis reactions. The hydrolysis breaks down the bond, separating the two amino acids. Even though the process is very slow, hydrolysis may occur in the presence of water.
What is the Difference Between Amide and Peptide Bond?
Amide and peptide bonds are biochemical bonds. The key difference between amide and peptide bond is that an amide bond forms between a hydroxyl group and an amino group of two molecules whereas a peptide bond forms between two amino acid molecules during the formation of a peptide chain.
Below infographic summarizes the difference between amide and peptide bond.
Summary – Amide vs Peptide Bond
In biochemistry, amide bonds and peptide bonds play a very important role in the formation of a protein molecule. The key difference between amide and peptide bond is that an amide bond forms between a hydroxyl group and an amino group of two molecules whereas a peptide bond forms between two amino acid molecules during the formation of a peptide chain.
Reference:
1. Helmenstine, Anne Marie. “Amide Definition and Examples in Chemistry.” ThoughtCo, Feb. 11, 2020, Available here.
Image Courtesy:
1. “Amide Bonds Amides V.1” By Jü – Own work (CC0) via Commons Wikimedia