The key difference between exoenzyme and endoenzyme is that exoenzyme is an enzyme secreted by a cell that functions outside that cell, while endoenzyme is an enzyme secreted by a cell that functions within that cell.
An enzyme is a protein that acts as a catalyst in living cells. It regulates the rate at which biochemical reactions proceed without being altered. All biochemical reactions that occur within living organisms are catalyzed by enzymes. An enzyme converts substrates into products. Normally, all metabolic reactions in the cell need enzyme catalysis in order to occur at rates fast enough to maintain cell activities. Exoenzyme and endoenzyme are two types of enzymes secreted by a cell.
CONTENT
1. Overview and Key Difference
2. What is an Exoenzyme
3. What is an Endoenzyme
4. Similarities – Exoenzyme and Endoenzyme
5. Exoenzyme vs Endoenzyme in Tabular Form
6. Summary – Exoenzyme vs Endoenzyme
What is an Exoenzyme?
Exoenzyme is an enzyme that functions outside the cell. Both prokaryotic and eukaryotic cells produce exoenzymes. Exoenzyme is a crucial component of many biological processes. Most often, an exoenzyme participates in the breakdown of larger macromolecules. The breakdown of larger macromolecules is a critical process that allows constituents to pass through the cell membrane and enter the cell.
Figure 01: Exoenzyme
In humans and other complex organisms, the digestion process is a well-known example of exoenzyme activity. Digestion is a complex process in which solid foods are broken down into smaller units by exoenzymes while passing through the digestive system. The generated small molecules then enter the cell and are utilized for various functions of the cell. Moreover, bacteria and fungi also produce exoenzymes to digest their nutrients. Therefore, these organisms are very useful to study the function of exoenzymes in the laboratory.
Some pathogenic species also use exoenzyme as a virulent factor. Exoenzymes assist in the spread of these pathogenic microorganisms. In addition to their role in the biological system, some microbial exoenzymes have been used by humans since ancient times for different purposes such as food production, textile production, biofuels, and paper industry. Furthermore, another important of microbial exoenzymes is the bioremediation of terrestrial and marine environments. Amylase, pectinase, lipase, pepsin, trypsin, coagulase, kinase, hyaluronidase, hemolysin, and necrotizing enzyme are some examples of exoenzymes.
What is an Endoenzyme?
Endoenzyme is an enzyme that functions within a cell. It is also called an intracellular enzyme. The majority of enzymes fall within this category. It is possible for a single enzyme to have both endoenzymatic and exoenzymatic functions.
Figure 02: Endoenzyme
For example, glycolytic enzymes of Kreb’s cycle have both functions. These enzymes typically catalyze millions of reactions that occur in the metabolic pathways, such as Kreb’s cycle in mitochondria and photosynthetic reactions in the chloroplast. Moreover, the lysosome contains many endoenzymes that are mainly responsible for destroying old cells.
What are the Similarities Between Exoenzyme and Endoenzyme?
- Exoenzyme and endoenzyme are two types of enzymes secreted by a cell.
- They are proteins.
- Both are made up of amino acids.
- They catalyze biochemical reactions.
- Both types of enzymes are present in eukaryotes as well as prokaryotes.
What is the Difference Between Exoenzyme and Endoenzyme?
Exoenzyme is an enzyme secreted by a cell that functions outside the cell, while endoenzyme is an enzyme secreted by a cell that functions within that cell. So, this is the key difference between exoenzyme and endoenzyme. Furthermore, exoenzyme is active outside the cell whereas endoenzyme is active inside the cell.
The following infographic lists the differences between exoenzyme and endoenzyme in tabular form for side by side comparison.
Summary – Exoenzyme vs Endoenzyme
Exoenzyme and endoenzyme are two types of enzymes that are secreted by a cell. Exoenzyme is active outside the cell while endoenzyme is active inside the cell. Thus, this is the key difference between exoenzyme and endoenzyme.
Reference:
1. Davis, Jack. “What Is an Exoenzyme?” News, 19 June 2020.
2. “Cell Enzyme.” Cell Enzyme – an Overview | ScienceDirect Topics.
Image Courtesy:
1. “C3 exoenzyme 2C8C” By E A S – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Lysosomes Digestion” By Jordan hawes – Own work (CC BY-SA 4.0) via Commons Wikimedia