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Title: | Non-conventional toxins from Elapid venoms | Authors: | Nirthanan, S. Gopalakrishnakone, P. Gwee, M.C.E. Khoo, H.E. Kini, R.M. |
Keywords: | Elapidae Muscle nicotinic acetylcholine receptor Neuronal α7 nicotinic acetylcholine receptor Non-conventional toxin Three-finger toxin Weak toxin |
Issue Date: | 1-Apr-2003 | Citation: | Nirthanan, S., Gopalakrishnakone, P., Gwee, M.C.E., Khoo, H.E., Kini, R.M. (2003-04-01). Non-conventional toxins from Elapid venoms. Toxicon 41 (4) : 397-407. ScholarBank@NUS Repository. | Abstract: | Non-conventional toxins constitute a poorly characterized class of three-finger toxins isolated exclusively from Elapidae venoms. These toxins are monomers of 62-68 amino acid residues and contain five disulfide bridges. However, unlike α/κ-neurotoxins and κ-neurotoxins which have the fifth disulfide bridge in their middle loop (loop II), the fifth disulfide bridge in non-conventional toxins is located in loop I (N-terminus loop). Overall, non-conventional toxins share ∼28-42% identity with other three-finger toxins including α-neurotoxins, α/κ-neurotoxins and κ-neurotoxins. Recent structural studies have revealed that non-conventional toxins also display the typical three-finger motif. Non-conventional toxins are typically characterized by a lower order of toxicity (LD50∼5-80mg/kg) in contrast to prototype α-neurotoxins (LD50∼0.04-0.3mg/kg) and hence they are also referred to as 'weak toxins'. Further, it is generally assumed that non-conventional toxins target muscle (α2βγδ) receptors with low affinities several orders of magnitude lower than α-neurotoxins and α/κ-neurotoxins. However, it is now known that some non-conventional toxins also antagonize neuronal α7 nicotinic acetylcholine receptors. Hence, non-conventional toxins are not a functionally homogeneous group and other, yet unknown, molecular targets for this class of snake venom toxins may exist. Non-conventional toxins may therefore be a useful source of ligands with novel biological activity targeting the plethora of neuronal nicotinic receptors as well as other physiological processes. © 2003 Elsevier Science Ltd. All rights reserved. | Source Title: | Toxicon | URI: | http://scholarbank.nus.edu.sg/handle/10635/102504 | ISSN: | 00410101 |
Appears in Collections: | Staff Publications |
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