Difference Between Peptides and Peptones

The main difference between peptides and peptones is that peptides are short chains of amino acids linked by peptide bonds whereas peptones are a class of peptides, the result of the proteolysis of animal milk or meat. Peptides are a mixture of dipeptides, tripeptides, tetrapeptide, etc. However, peptones contain fats, salts, metals, vitamins, etc. In addition, peptides serve as hormones, neuropeptides, alkaloids, antibiotics, and structural molecules. But, peptones serve as a source of nitrogen and carbon. 

Peptides and peptones are two types of molecules that emerge as a result of the hydrolysis of proteins. Both are made up of amino acids. The basic elements of both are carbon, oxygen, hydrogen, nitrogen, and sulfur.  

Key Areas Covered 

1. What are Peptides
     – Definition, Structure, Importance
2. What are Peptones
    – Definition, Structure, Importance
3. What are the Similarities Between Peptides and Peptones
     – Outline of Common Features
4. What is the Difference Between Peptides and Peptones
     – Comparison of Key Differences

Key Terms: Amino Acids, Peptide Bonds, Peptides, Peptones, Proteins

What are Peptides 

Peptides are compounds with two or more amino acids linked in a chain; the carboxyl group of each acid is joined to the amino group of the next by a bond of the type -OC-NH-. This bond type is called peptide bonds. In fact, proteins are polypeptides. The five classes of peptides are milk peptides, ribosomal peptides, nonribosomal peptides, peptones, and peptide fragments.  

1. Milk peptides – Formed from milk protein, casein. 
2. Ribosomal peptides – Formed from the proteolytic digestion of polypeptides synthesized during the translation of mRNA 
3. Nonribosomal proteins – Assembled by the enzymes, but not from the translation of mRNA (ex: Glutathione) 
4. Peptones – Formed from the proteolytic digestion of animal milk or meat 
5. Peptide fragments – Protein fragments used in the identification or quantification of the protein source 
   

   Figure 1: Tetrapeptide

Peptides are functional molecules in the body that serve as hormones, neuropeptides, alkaloids, and, antibiotics. They also serve as structural molecules in the cell. 

What are Peptones 

Peptones refer to the soluble proteins formed in the early stage of protein breakdown during digestion. The digestive enzymes of the gastric and pancreatic juice are responsible for the breakdown of proteins into peptones. Peptones are chemically synthesized by boiling a protein source with water and diluted acids. The three types of pure peptones are amphopeptone, antipeptone, and hemipeptone. 

Figure 2: Agar Plate with Tryptone

Peptones are an ingredient of the nutrient media used for bacteria and fungi. Tryptone is such peptone commonly used in molecular biology. It is formed by the digestion of casein. 

Similarities Between Peptides and Peptones 

• Peptides and peptones are two types of proteinsmade up of amino acids. 
• The elements of peptides and peptones are carbon, hydrogen, oxygen, nitrogen, and sulfur. 
• Both are degradation products of the hydrolysis of proteins.  
• They do not precipitate with ammonium sulfur. 

Difference Between Peptides and Peptones 

Definition 

Peptides: Compounds with two or more amino acids linked in a chain, the carboxyl group of each acid being joined to the amino group of the next by a bond of the type -OC-NH-

Peptones: Soluble proteins formed in the early stage of protein breakdown during digestion.

Significance 

Peptides: Short chains of amino acids 

Peptones: A class of peptides 

Derived from 

Peptides: There are several classes of peptides based on the way they are produced

Peptones: Proteolysis of animal milk or meat 

Composition 

Peptides: Dipeptides, tripeptides, tetrapeptides, etc. 

Peptones: In addition to small peptides contain fats, salts, metals, vitamins, etc. 

Types 

Peptides: The five classes of peptides are milk peptides, ribosomal peptides, nonribosomal peptides, peptones, and peptide fragments

Peptones: The three types of pure peptones are amphopeptone, antipeptone, and hemipeptone 

Importance 

Peptides: Serve as hormones, neuropeptides, alkaloids, antibiotics, and structural molecules

Peptones: Used in nutrient media for the growth of bacteria and fungi 

Conclusion 

Peptides are short chains of amino acids whereas peptones are a class of peptides that are made up of the proteolysis of animal milk or meat. Both peptides and peptones are the results of the hydrolysis of proteins. The main difference between peptides and peptones is the formation and the composition. 

Reference:

1. “Peptide.” Nature News, Nature Publishing Group, Available Here
2. “Peptone.” Fine Dictionary, Available Here

Image Courtesy:

1. “Tetrapeptide structural formulae” By Ipatrol – Own work (CC0)  via Commons Wikimedia
2. “Rhizobium tropici strain BR816 on TY agar” By Ninjatacoshell – Own work (CC BY-SA 3.0) via Commons Wikimedia