microbial, plant and animal toxins Flashcards
what does the botulinus toxin target
peripheral nerves
what is the structure of active botulin
50 kDa light chain covalently linked through a disulphide bond to a 100 kDa heavy chain
what is the structure of type 2 ribosome inactivating proteins
two polypeptide chains linked together by a disulphide bridge
what is an example of a type 2 ribosome inactivating protein
ricin
where is ricin found
in seeds of the castor oil plant, Ricinus communis
is ricin cytotoxic
yes
which chain of ricin has enzymatic activity
A
what does ricin A chain do
de-adenylates 28s rRNA
What activity does ricin A chain have
DNA lyase activity
what does snake venom alpha inhibit and where
binding of acetylcholine to nicotinic acetylcholine receptor at the skeletal neuromuscular junction
what do many snake venoms contain
enzymes that breakdown the connective tissue matrix at the sit of envenomation
what do snake venom beta toxins block
neuromuscular transmission via an action on the presynaptic nerve terminal = acetylcholine release
what does the light chain of botulin target and cleave
SNARE proteins
what is used to treat venom
antivenoms
what is there a risk of after administration of an antivenom
sever hypersensitivity reaction
what can anticholinesterase drugs be useful to treat
reduction of the effects of snake venom
what happens to ricin within target cells
it is transferred from the golgi complex to endoplasmic reticulum
what happens to the ricin ?A chain
transported out of the endoplasmic reticulum into the cytosol
what do amatoxins cause
inhibition of RNA polymerase = inhibiton of protein synthesis
what are amatoxins target cells
hepatocytes
what is another name for fungus claviceps purpurea
ergot
what can ergotism result in
gangrene
examples of pharmacologically active ergot alkaloids (2)
ergometrine
ergotamine
what is ergotamine used to treat
migraine
where is the word botulinism derivered from
botulus
what spore causes botulinism
clostridium botulinum
what is infant botulinism caused by
children ingesting food contaminated with bacterial spores
how are antivenomes normally given
by IV, for speed
does the transport of ricin out of the ER to the cytsol require both A and B chain
no just A
how long does death take after amatoxins
several days
