Furthermore, they are specific to certain bacterial strains. Both gram-negative and gram-positive bacteria produce exotoxins.Įxotoxins are more toxic than endotoxins. Therefore, exotoxins are considered an extracellular component. They are secreted to the cell surrounding during their exponential growth or during cell lysis. A small amount of exotoxins is enough to generate toxicity. Being an enzyme, it can catalyze many biochemical reactions, and it is reusable. What is Exotoxin?Įxotoxins are soluble proteins which can act as enzymes. Furthermore, endotoxins are poor antigens. It has an adhesive function on a host when colonizing. Hence, endotoxins are a part of this protective function. The outer membrane of bacteria is impermeable to large molecules and hydrophobic molecules and is protected from the external environment. In addition, endotoxins are less potent and less specific on their substrate. However, since they are not proteins, they do not have an enzymatic function. In these lipopolysaccharides, the lipid portion (Lipid A) has the toxicity while the polysaccharide portion has the immunogenicity. This complex lipopolysaccharide has a core polysaccharide chain, O-specific polysaccharide side chain, and a lipid component. These toxins are released from growing bacteria or released due to activities of certain antibiotics, or at the function of phagocytic digestion. Moreover, bacteria should not be essentially pathogenic to have endotoxins. In gram-negative bacteria, endotoxin exists in the outer membrane of the cell wall. Side by Side Comparison – Endotoxin vs Exotoxin in Tabular FormĮndotoxins are lipopolysaccharides, which can be seen in gram-negative pathogenic bacteria such as Escherichia coli, Salmonella, Shigella, Pseudomonas, Neisseria, Haemophilus influenza, and Vibrio cholerae. Similarities Between Endotoxin and Exotoxinĥ. Generally, endotoxins are lipopolysaccharides while exotoxins are proteins. Furthermore, they act differently on living organisms. There is a difference between endotoxin and exotoxin structurally as well as chemically. There are two types of bacterial toxins as endotoxins and exotoxins. It is one of the main mechanisms bacteria use to cause diseases. Toxigenesis is the process of producing toxins by pathogenic bacteria. The key difference between endotoxin and exotoxin is that the endotoxin is a lipopolysaccharide that lies within the bacterial cell wall while exotoxin is a protein that secretes to the outside of the bacterial cell.
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