Wednesday 11 July 2012

172.IN BOTULINISM IT BLOCKS

A.POST SYNAPTIC INHIBITION
B.INHIBIT ACETYL CHOLINE RELEASE
C.INHIBITS ACETYL CHOLINE ESTERASE
D.

ANS:INHIBIT RELEASE OF ACETYL CHOLINE

There are seven serologically distinct toxin types, designated A through G. Additionally, six of the seven toxin types have subtypes with five subtypes of BoNT A having been described. The toxin is a two-chain polypeptide with a 100-kDa heavy chain joined by a disulfide bond to a 50-kDa light chain. This light chain is an enzyme (a protease) that attacks one of the fusion proteins (SNAP-25, syntaxin or synaptobrevin) at a neuromuscular junction, preventing vesicles from anchoring to the membrane to release acetylcholine. By inhibiting acetylcholine release, the toxin interferes with nerve impulses and causes flaccid (sagging) paralysis of muscles in botulism, as opposed to the spastic paralysis seen in tetanus.

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