|
DIFFERENCES BETWEEN BACTERIAL ENDOTOXINS AND
EXOTOXINS
|
|
ENDOTOXIN
|
EXOTOXIN
|
|
Chemical
nature
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Lipopolysaccharide
|
Protein
|
|
Molecular
weight
|
10kDa
|
50-1000kDa
|
|
Relationship
to cell
|
Part of outer
membrane
|
Extracellular,
diffusible
|
|
Effect of
boiling
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Not denatured
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Gets denatured
|
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Can be
toxoided
|
No
|
Yes
|
|
Potency
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Low
(>100μg)
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High (1
μg)
|
|
Specificity
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Low
|
High
|
|
Enzymatic
activity
|
No
|
Mostly
|
|
Pyrogenicity
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Yes
|
Occasionally
|
|
Produced by
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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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