ISSN:
1435-1463
Keywords:
Botulinum neurotoxin
;
cholinergic synaptosomes
;
Torpedo electric organ
;
acetylcholine release
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Torpedo electric organ has been used to study the binding of botulinum neurotoxin type A to pure cholinergic synaptosomes and presynaptic plasma membrane.125I-labeled botulinum neurotoxin type A exhibits specific binding to cholinergic fractions. Two binding sites have been determined according to data analysis: a high affinity binding site (synaptosomes: Kd=0.11±0.03 nM, Bmax=50±10 fmol · mg prot−1; presynaptic plasma membrane: Kd=0.2±0.05 nM, Bmax=150±15 fmol · mg prot−1) and a low affinity binding site (synaptosomes: Kd ≈ 26 nM, Bmax ≈ 7.5 pmol · mg prot−1; presynaptic plasma membrane: Kd ≈ 30 nM, Bmax ≈ 52 pmol · mg prot−1). The binding of125I-botulinum neurotoxin type A is decreased by previous treatment of synaptosomes by neuraminidase and trypsin, and by a preincubation with bovine brain gangliosides or antiserum raised against Torpedo presynaptic plasma membrane. When presynaptic plasma membranes are blotted to nitrocellulose sheet, either125I-botulinum neurotoxin or botulinum toxin-gold complexes bind to a Mr ≈ 140,000 protein. Botulinum toxin-gold complexes have also been used to study the toxin internalization process into Torpedo synaptosomes. The images fit the three step sequence model in the pathway of botulinum neurotoxin poisoning.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01250791
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