What is the Difference Between Protease and Peptidase

The main difference between protease and peptidase is that protease is a hydrolytic enzyme that hydrolyzes peptide bonds, whereas peptidase is one of the two types of proteases that hydrolyzes peptide bonds at the terminal amino acid. Furthermore, the second type of proteases is proteinase, which hydrolyzes internal peptide bonds. Proteinases are also known as endopeptidases, and they act best on intact proteins while peptidases are also known as exopeptidases and they prefer small peptides. 

Protease and peptidase are two types of proteolytic enzymes that hydrolyze peptide bonds between amino acids. 

Key Areas Covered 

1. What is a Protease
     – Definition, Types, Importance
2. What is a Peptidase
     – Definition, Types, Importance
3. What are the Similarities Between Protease and Peptidase
     – Outline of Common Features
4. What is the Difference Between Protease and Peptidase
     – Comparison of Key Differences

Key Terms 

Endopeptidase, Exopeptidase, Peptidase, Protease, Proteinase

What is a Protease 

Protease is an enzyme that hydrolyzes peptide bonds in proteins. Therefore, this enzyme helps in protein catabolism and proteolysis. It is important in digestion and immune system as well. Generally, proteases occur in all types of life forms. 

Figure 1: Pepsin + Inhibitor (Blue)

Furthermore, the two main types of proteases are endopeptidases and exopeptidases. Basically, endopeptidases are endo-acting peptide bond hydrolases. They are also known as proteinases. Additionally, they prefer intact proteins and result in oligopeptides. Exopeptidases are also known as peptidases. 

What is a Peptidase 

A peptidase is an exopeptidase, a type of protease. Significantly, it hydrolyzes terminal peptide bonds. Therefore, it is an exo-acting bond hydrolase. It also results in a single amino acid or a dipeptide.

Figure 2: Carboxypeptidase A 

Moreover, there are two types of peptidases based on the type of terminus they hydrolyze. Basically, they are aminopeptidases, which hydrolyze terminal peptide bonds in the amino-terminal, and carboxypeptidases, which hydrolyze terminal peptide bonds in the carboxy-terminal. Furthermore, aminopeptidases occur in the brush border of the small intestine. On the other hand, carboxypeptidases occur in the pancreatic juice of the digestive system. 

Similarities Between Protease and Peptidase 

• Protease and peptidase are two types of proteolytic enzymes. 
• They can hydrolyze peptide bonds between amino acids. 
• Also, both play a significant function in protein digestion in the digestive system. 
• Moreover, they are most abundant in animals but, also present in plants, fungi, bacteria, and viruses. 

Difference Between Protease and Peptidase 

Definition 

Protease refers to an enzyme that breaks down proteins and peptides, while peptidase refers to an enzyme that breaks down peptides into amino acids. Thus, this is the main difference between protease and peptidase.

Significance 

Protease is a hydrolytic enzyme that hydrolyzes peptide bonds, while peptidases are a type of proteases. 

Types 

Besides, the two types of proteases are endopeptidases and exopeptidases while peptidase is an exopeptidase. 

Hydrolysis of Peptide Bonds 

Moreover, endopeptidases hydrolyze internal peptide bonds, while peptidases hydrolyze peptide bonds at the end. 

Type of Substrates 

Also, another difference between protease and peptidase is that endopeptidases prefer intact proteins, while peptidases prefer small peptides. 

Result in 

Endopeptidases result in oligopeptides while peptidases result in a single amino acid or dipeptide. 

Examples 

Some examples of endopeptidases are pepsin, trypsin, chymotrypsin, papain, elastase, etc., while some examples of peptidases are aminopeptidases, carboxypeptidase A, etc. 

Conclusion 

Protease is an enzyme that hydrolyzes peptide bonds between amino acids. Moreover, the two types of proteases are endopeptidases and exopeptidases. Endopeptidases are also known as proteinases. They hydrolyze internal bonds in the intact proteins. On the other hand, exopeptidases are also known as peptidases. They hydrolyze terminal peptide bonds. Therefore, the main difference between protease and peptidase is the location of peptide bonds they hydrolyze. 

References:

1. Barrett, A J, and J K McDonald. “Nomenclature: protease, proteinase and peptidase.” The Biochemical journal vol. 237,3 (1986): 935. doi:10.1042/bj2370935.

Image Courtesy:

1. “1pso” By Deposition authors: Fujinaga, M., Chernaia, M.M., Tarasova, N., Mosimann, S.C., James, M.N.G.;visualization author: User:Astrojan (CC BY 4.0) via Commons Wikimedia   
2. “Carboxypeptidase A” By Lijealso – Created using the data from Protein Data Bank (PDB: 1CPX) and rendered using Pymol. (Public Domain) via Commons Wikimedia