What is the Difference Between Peptides and Amino Acids

The key difference between peptides and amino acids is that peptides consist of peptide bonds that link amino acids, while amino acids are individual molecules that do not have peptide linkages.

There are essential organic compounds important for the formation and existence of life. These organic molecules become the building blocks of life. Amino acids and peptides are two such compounds, extremely important for the synthesis of different compounds. Amino acids and peptides consist of different structural and functional differences along with many similarities.

CONTENTS

1. Overview and Key Difference
2. What are Peptides 
3. What are Amino Acids
4. Similarities – Peptides and Amino Acids
5. Peptides vs Amino Acids in Tabular Form
6. Summary – Peptides vs Amino Acids

What are Peptides?

Peptide is a combination of amino acids. The amino acids in a peptide are linked through peptide bonds. A peptide bond is an amide-type covalent bond that links two consecutive alpha-amino acids from carbon number one (C1) of one alpha-amino acid and nitrogen number two (N2) of another.

During the formation of the peptide bond between amino acids, a water molecule is released. Peptides are of two types depending on the number of amino acids. They are oligopeptides, which consist of 2-10 amino acids, and polypeptides, which consist of 10-50 amino acids.

The function of peptides in the human body is extremely important. Peptides function as hormones (peptide hormones) in the body. These hormones include antidiuretic hormone (vasopressin), oxytocin, and angiotensin. The medical uses of peptides include antioxidant, antimicrobial, and antithrombotic (anti-clotting) effects. Peptides are important as dietary supplements that help in antiaging, improved wound healing, and cosmetic applications.

What are Amino acids?

Amino acid is an organic molecule that consists of a basic amino group (―NH2), an acidic carboxyl group (―COOH), and an organic R group (or side chain). The side chain is unique to each amino acid. The basic elements present in amino acids include carbon, hydrogen, oxygen, and nitrogen. In addition to these basic elements, certain amino acids such as cysteine, methionine, and selenium consist of sulphur as a basic element in addition to carbon, hydrogen, oxygen, and nitrogen.

Amino acids, in combination, lead to the formation of different proteins. Therefore, amino acids are the building unit of life and are categorized into three groups. They are essential amino acids, non-essential amino acids, and conditional amino acids. Essential amino acids include 9 amino acids. They cannot be synthesized in the body and should be taken from the diet. The 9 essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Non-essential amino acids include alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine. Conditional amino acids become only essential during special instances such as illnesses or stress. These include arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline, and serine. Different codons in the genetic code code for the synthesis of different amino acids.

What are the Similarities Between Peptides and Amino Acids?

• • Peptides and amino acids are two types of organic molecules.

• They are present in the cell.
• Carbon, hydrogen, oxygen, nitrogen, and sometimes sulphur form the elemental composition of both peptides and amino acids.
• Both are important for the function of the cell.
• Moreover, they act as precursors of proteins.

What is the Difference Between Peptides and Amino Acids?

Peptides consist of peptide bonds that link amino acids, while amino acids are individual molecules that do not have peptide linkages. Thus, this is the key difference between peptides and amino acids. Peptides are of two types: oligopeptides and polypeptides. Amino acids are of three types: essential amino acids, non-essential amino acids, and conditional amino acids. Moreover, peptides consist of 2-50 amino acids linked with peptide bonds, while amino acids consist of a basic amino group (―NH2), an acidic carboxyl group (―COOH), and an organic R group (or side chain).

The below infographic presents the differences between peptides and amino acids in tabular form for side-by-side comparison.

Summary – Peptides vs Amino Acids

Peptides and amino acids are precursors of proteins. Peptides consist of peptide bonds that link amino acids, while amino acids are individual molecules that do not have peptide linkage. Peptide is a combination of 2-50 amino acids. Amino acid is an organic molecule consisting of a basic amino group (―NH2), an acidic carboxyl group (―COOH), and an organic R group (or side chain). Peptides are of two types as oligopeptides and polypeptides. Amino acids are of three types as essential amino acids, non-essential amino acids, and conditional amino acids. So, this summarizes the difference between peptides and amino acids.

Reference:

1. Ajiboye, Tolu. “What Is a Peptide?” Verywell Health.
2. “Amino Acid.” Encyclopædia Britannica, Encyclopædia Britannica, Inc.

Image Courtesy:

1. “Classification Of Peptidomimetics” By Prof. Dr. Tom N. Grossmann – (CC BY-SA 4.0) via Commons Wikimedia
2. “L-amino acid any” By Incnis Mrsi – Own work, based on PD File:L-valine-3D-balls.png (CC0) via Commons Wikimedia