TAILIEUCHUNG - Báo cáo khoa học: A synthetic weak neurotoxin binds with low affinity to Torpedo and chicken a7 nicotinic acetylcholine receptors

Weak neurotoxins from snake venom are small proteins with five disulfide bonds, which have been shown to be poor bindersof nicotinicacetylcholine report on the cloning and sequencing of four cDNAs encoding weak neurotoxins fromNaja sputatrixvenomglands. The protein encoded by one of them, Wntx-5, has been synthesized by solid-phase synthesis and characterized. | Eur. J. Biochem. 269 4247-4256 2002 FEBS 2002 doi A synthetic weak neurotoxin binds with low affinity to Torpedo and chicken a7 nicotinic acetylcholine receptors Siew Lay Poh1 2 Gilles Mourier1 Robert Thai1 Arunmozhiarasi Armugam2 Jordi Molgo3 Denis Servent1 Kandiah Jeyaseelan2 and Andre Menez1 CEA Saclay Gif-sur-Yvette France 2National University of Singapore Singapore 3UPR CNRS Gif-sur-Yvette France Weak neurotoxins from snake venom are small proteins with five disulfide bonds which have been shown to be poor binders of nicotinic acetylcholine receptors. We report on the cloning and sequencing of four cDNAs encoding weak neurotoxins from Naja sputatrix venom glands. The protein encoded by one of them Wntx-5 has been synthesized by solid-phase synthesis and characterized. The physicochemical properties of the synthetic toxin sWntx-5 agree with those anticipated for the natural toxin. We show that this toxin interacts with relatively low affinity Kd 180 nM with the muscular-type acetylcholine receptor of the electric organ of T. marmorata and with an even weaker affinity 90 M with the neuronal a7 receptor of chicken. Electrophysiological recordings using isolated mouse hemidiaphragm and frog cutaneous pectoris nerve-muscle preparations revealed no blocking activity of sWntx-5 at M concentrations. Our data confirm previous observations that natural weak neurotoxins from cobras have poor affinity for nicotinic acetylcholine receptors. Keywords snake neurotoxins nicotinic acetylcholine receptors. During the past three decades the most obvious venom toxins have been uncovered either because they are present in large amounts and or because they have been directly associated with the search for an important target. At present two additional approaches may be considered to discover new toxin functions. One of them is a proteomic-type approach which aims at isolating all components of the toxinome 1 2 . The second approach involves .

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