Difference Between Endotoxins And Exotoxins

The toxin is produced in the human body or any living organism that is a poisonous material includes protein and peptides. Toxins are present and can function in a variety of ways, including Lipopolysaccharide (LPS) is the most powerful endotoxin. First, the one that is associated with the cell wall of Gram-negative bacteria is known as lipopolysaccharide, whereas the other is proteins, that act on tissue sites after being released from the bacterial cell. Therefore, endotoxins are cell-associated toxins, while exotoxins are extracellular diffusible toxins. Bacterial toxins are some kinds of proteins capable of performing various tasks. Bacterial proteins function as individual molecular devices, targeting the specific cell of an organism and destroying them in some other way. Toxins can trigger the host in multiple ways, i.e, by activating immune responses (S, aureus superantigens), inhibiting protein synthesis (diphtheria toxin), activating secondary messaging pathways (cholera toxin), damaging the cell membrane (E. coli hemolysin), or even by the action of metalloprotease activity (tetanus toxin). Toxins are categorized into two types:

  • Endotoxins
  • Exotoxins

The major difference between Endotoxins And Exotoxins is that endotoxins are lipopolysaccharide-protein (LPS) complexes, responsible for forming an integral part of the cell wall of gram-negative bacteria. On the other hand, exotoxins are the proteins secreted by a few species of bacteria. In this article, you will learn the points where the two endotoxins and exotoxins of the two toxins differ with a brief description of them.

Difference Between Endotoxins And Exotoxins in Tabular Form



Endotoxins are lipopolysaccharide-protein (LPS) complexes, responsible for forming an integral part of the cell wall of gram-negative bacteria. These are proteins secreted by a few species of bacteria.
Part of cells. Released from the cell.
The molecular weight of endotoxins is about 50-1000 KDa. The molecular weight of exotoxins is about 10 KDa.
Composed of a Lipoglycan complex. Composed of polypeptides or Protein.
Thermostable and active at 250 ° C or even 1000 ° C. Susceptible to heat and are destroyed beyond 60-80 ° C.
Weakly immunogenic. Highly immunogenic.
The location in the genesis on the bacterial chromosome. located in plasmid or bacteriophage genes.
does not produce toxoids. Produces toxoids.
Examples: Salmonella typhi, E. coli, Vibrio cholera, Shigella. Examples: Bacillus cereus, Bacillus anthracis, Staphylococcus aureus, Streptococcus pyogenes.


Endotoxins are lipopolysaccharide (LPS) proteins released by Gram bacteria. They are bound to cells and thus formed only if the cell is lysed. Endotoxins are present in the outer covering of the cell wall in Gram bacteria. Endotoxins are present in E. coli, Shigella, Salmonella, Pseudomonas, Haemophilus influenza, Neisseria, and Vibrio cholerae and also called lipopolysaccharides (LPS). Endotoxins are secreted if bacteria grow duw to the actions of specific antibiotics. Hence, endotoxins are present in the outer membrane of the bacteria. The responsible for the structure of bacteria, it is recommended as a cell-associated substance. The lipopolysaccharide (LPS) discharges at the bacterial cell death.  The toxicity is related to the lipid component in endotoxins on the other side immunogenicity is related to polysaccharide components. The LPS gives rise to various inflammation and activates complement by the alternative pathway.

Endotoxins Function

  • Endotoxins play an vital role in increasing the natural immunity.
  • Endotoxins have the function of sticking to a host during the time of colonization.
  • Endotoxins show little antigenicity.


The toxins that are relaesed extracellularly with the development of the organism. Exotoxins are contagious toxins that spread through the source of infection to other body parts and cause harm. Exotoxins are soluble proteins which act as enzymes. It has a ability to cause damage/harm to thr host by destroying cells or interfering with normal cellular metabolism.These toxins are powerful that cause extreme damage to the host. Exotoxins play a important role in rapid growth or during their cell lysis. Gram + and Gram bacteria both can produce exotoxins.

Types of Exotoxins

There are 3 main categories of exotoxins, and these types indicate about the location of the activity

  • Enterotoxins
  • Neurotoxins
  • Cytotoxins

Exotoxins Function

  • Clostridium botulinum, Clostridium tetani, and Corynebacterium diphtheriae produce exotoxins.
  • Exotoxins activate the immune system and secrete antitoxins to nullify the toxin.

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