Journal
TOXICON
Volume 52, Issue 1, Pages 163-174Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.toxicon.2008.05.001
Keywords
alpha-bungarotoxin biotin-XX conjugate (Biotin-BgTx); anatoxin-a; cyanobacteria; homoanatoxin-a; nicotinic acetylcholine receptor (nAChR); Torpedo electrocyte membranes
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Funding
- Institut Pasteur [PTR 2000/25]
- CNRS [URA 2172, URA 2182]
- College de France
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Anatoxin-a (ANTX) and homoanatoxin-a (HANTX), neurotoxins exclusively produced by cyanobacteria (LD(50) 200-250 mu g kg(-1), i.p. mouse), are agonists of the nicotinic acetylcholine receptors (nAChRs) to which they tightly bind. We have exploited the high affinity of these neurotoxins for the nicotinic receptors to develop a non-radioactive ligand-binding assay using Torpedo electrocyte membranes and biotinylated alpha-bungarotoxin (Biotin-BgTx) as tracer for detection of this class of toxins. The affinity of the Torpedo nAChRs for Biotin-BgTx was determined by chemiluminescence (K(d) = 1.2 x 10(-8) M Biotin-BgTx) or color development (K(d) = 3.5 x 10(-8) M Biotin-BgTx). Binding of ANTX or HANTX to the nAChRs competitively inhibits the binding of Biotin-BgTx to the receptors in a concentration-dependent manner (chemiluminescence: IC(50): 6.2 x 10(-8) M ANTX; color development: IC(50): 1.7 x 10(-8) M ANTX). The proposed method was validated by HPLC/MS with detection in the single ion recording mode. The non-radioactive ligand receptor-binding assay was successfully applied to the analysis of extracts prepared from cyanobacteria in culture and from natural habitats, as well as from aqueous samples. This method is suitable for ANTX and HANTX early survey of environmental samples since it requires minimal manipulations, is highly sensitive and gives consistent signal-to-noise ratios. (C) 2008 Elsevier Ltd. All rights reserved.
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