Snake venom toxins

Chu N. (2005) Contribution of a snake venom toxin to myasthenia gravis The discovery of alpha-bungarotoxin in Taiwan. J Hist Neurosci 14 138-148. 

Of this family of peptides containing two intramolecular disulfide bonds the most studied in terms of oxidative refolding are a-conotoxins with two adjacent cysteine residues, i.e. with m = 0, the bee venom toxins, for example apamin and mast cell degranulating peptide, and snake venom toxins, exemplified by sarafotoxins, and endothelins, mammalian peptide hormones with the characteristic Cys-(Xaa)rCys/Cys-(Xaa)3-Cys motif (Scheme 2). With m = 0 or 1 all these peptides are expected to show a weak tendency to form the isomer 3 with a disulfide bond between two proximal cysteine residues. This was fully confirmed by oxidative refolding experiments. 

Various types of proteins have been purified using hydrophobic interaction chromatography including alkaline phophatase, estrogen receptors, isolectins, strepavidin, calmodulin, epoxide hydrolase, proteoglycans, hemoglobins, and snake venom toxins (46). In the case of cobra venom toxins, the order of elution of the six cardiotoxins supports the hypothesis that the mechanism of action is related to hydrophobic interactions with the phospholipids in the membrane. 

Strydom, D.J. (1976). Snake venom toxins. Purification and properties of low-molecular-weight polypeptides of Dendroaspis polylepis polylepis (black mamba) venom. Eur. J. Biochem. 69 169-76. 

Kryger, G., Harel, M., Giles, K., Toker, L., Velan, B., Lazar, A., Kronman, C., Barak, D., Ariel, N., Shafferman, A., Silman, L, Sussman, J.L. (2000). Structures of recombinant native and E202Q mutant human acetylcholinesterase complexed with the snake-venom toxin fasciculin-II. Acta Crystallogr. D Biol. Crystallogr. 56 (Pt 11) 1385-94. 

Heinlein, U. A.O., Wallat, S., Senftleben, A., and Lemaire, L. (1994). Male germ cell-expressed mouse gene T AZ83 encodes a putative, cysteine rich transmembrane protein (cyritestin) sharing homologies with snake venom toxins and sperm egg fusion proteins. Dev. Growth and Diff. 36 49-58. 

A modified version of the Computer Automated Structure Evaluation (CASE) program has been successfully applied to the study of the neurotoxic and cytotoxic activity of the snake venom toxins. The program identified the sites that seem to be the most relevant to the activity of these two classes of peptides. The knowledge of the three dimensional structure of these peptides together with the relevant fragments selected by the CASE program helped to clarify the differences between the activity of each type of toxin. 

The 93- to 95-residue neurophysins act as carriers for vasopressin and ocytocin, forming specific complexes with them. Neurophysins contain 14 cysteine residues, which form seven disulfide bonds. There is a striking similarity in sequence between the neurophysins, snake venom toxins, a wheat germ lectin (agglutinin), a ragweed pollen allergen, and a small plant protein called hevein. On the basis of the alignment of cysteine residues, Drenth proposed that all of these proteins have a disulfide-linked core whose structure is shown in Fig. 30-16. 

Medical personnel must remember, however, that with the advances of molecular genetics, it is possible to clone and produce many natural neurotoxins in relatively large quantities. For the present (1996), botulinum poisoning is a much more likely biological warfare agent than snake venom toxins. In future years, other (cloned) neurotoxins should be considered in the diagnosis. 

Selvanayagam ZE and Gopalakrishnakone P (1999) Test for detection of snake venoms, toxins and venom antibodies Review on recent trends (1987-1997). Toxicon 37 565-586. 

Loring, R. H., Andrews, D., Lane, W., and Zigmond, R. E. (1986). Amino acid sequence of toxin F, a snake venom toxin that blocks neuronal nicotinic receptors. Brain Res. 385 30-37. 

Mebs, D. (1988) Snake venom toxins Structural aspects, in "Neurotoxins in Neurochemistry" (Dolly, J. O., ed.) Ellis Horwood, Chichester, England, pp. 3-12. 

Osorio e Castro, V. R. and Vernon, L. R, 1989, Hemolytic activity of thionin from Pyrularia pubera nuts and snake venom toxins of Naja Naja species pyrularia thionin and snake venom cardiotoxin compete for the same membrane site, Toxicon, 27 511. 

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