Toxins' heat stability

[a_zed24]

Hello there,
I know endotoxins are heat stable while exotoxins are not.
But why's that?
What particular feature do the endotoxins have to resist heat? Is it because the are mainly made of lipid and saccharides, and don't "denature" like proteins? Maybe it's a silly question, sorry about that

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[Lawpy]

Hello there,
I know endotoxins are heat stable while exotoxins are not.
But why's that?
What particular feature do the endotoxins have to resist heat? Is it because the are mainly made of lipid and saccharides, and don't "denature" like proteins? Maybe it's a silly question, sorry about that

Here is a good chart comparing endotoxins and exotoxins.

As you can see, exotoxins are proteins while endotoxins are lipopolysaccharides. Exotoxins are generally unstable in high temperatures because heat breaks the hydrogen bonds that contribute to the secondary/tertiary/quaternary structure of the proteins. In contrast, endotoxins consist of polysaccharides that are covalently bonded to a core oligosaccharide (has a short chain of monosaccharides), and this core oligosaccharide is covalently bonded to a lipid A backbone. Since covalent bonds are stronger than hydrogen bonds, it requires more energy to break the covalent bonds linking the endotoxins together, and thus endotoxins are generally considered to be heat stable.

There are some exotoxins called heat-stable enterotoxins that can remain active under high temperatures, but generally, endotoxins are heat stable.

For reference, here is the structure of a typical endotoxin.

 

[a_zed24]

Here is a good chart comparing endotoxins and exotoxins.

As you can see, exotoxins are proteins while endotoxins are lipopolysaccharides. Exotoxins are generally unstable in high temperatures because heat breaks the hydrogen bonds that contribute to the secondary/tertiary/quaternary structure of the proteins. In contrast, endotoxins consist of polysaccharides that are covalently bonded to a core oligosaccharide (has a short chain of monosaccharides), and this core oligosaccharide is covalently bonded to a lipid A backbone. Since covalent bonds are stronger than hydrogen bonds, it requires more energy to break the covalent bonds linking the endotoxins together, and thus endotoxins are generally considered to be heat stable.

There are some exotoxins called heat-stable enterotoxins that can remain active under high temperatures, but generally, endotoxins are heat stable.

For reference, here is the structure of a typical endotoxin.

Thank you a lot, much appreciated!