MICROBIOLOGY NOTES

 

   

DIFFERENCES BETWEEN BACTERIAL ENDOTOXINS AND EXOTOXINS

 

ENDOTOXIN

EXOTOXIN

Chemical nature

Lipopolysaccharide

Protein

Molecular weight

10kDa

50-1000kDa

Relationship to cell

Part of outer membrane

Extracellular, diffusible

Effect of boiling

Not denatured

Gets denatured

Can be toxoided

No

Yes

Potency

Low (>100μg)

High (1 μg)

Specificity

Low

High

Enzymatic activity

No

Mostly

Pyrogenicity

Yes

Occasionally

Produced by

Gram negative bacteria

Many gram positive bacteria and few gram negative bacteria

Antigenicity

Poor

Good

Detection by

Limulus lysate assay

Many tests (precipitation, neutralization etc.)


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    Last edited in June 2006