1h5o: Difference between revisions

[[Image:1h5o.gif|left|200px]]<br /><applet load="1h5o" size="350" color="white" frame="true" align="right" spinBox="true"  

Crotamine is a component of the venom of the snake Crotalus durissus terrificus and it belongs to the myotoxin protein family. It is a 42 amino acid toxin cross-linked by three disulfide bridges and characterized by a mild toxicity (LD50 = 820 micro g per 25 g body weight, i.p. injection) when compared to other members of the same family. Nonetheless, it possesses a wide spectrum of biological functions. In fact, besides being able to specifically modify voltage-sensitive Na+ channel, it has been suggested to exhibit analgesic activity and to be myonecrotic. Here we report its solution structure determined by proton NMR spectroscopy. The secondary structure comprises a short N-terminal alpha-helix and a small antiparallel triple-stranded beta-sheet arranged in an alphabeta1beta2beta3 topology never found among toxins active on ion channels. Interestingly, some scorpion toxins characterized by a biological activity on Na+ channels similar to the one reported for crotamine, exhibit an alpha/beta fold, though with a beta1alphabeta2beta3 topology. In addition, as the antibacterial beta-defensins, crotamine interacts with lipid membranes. A comparison of crotamine with human beta-defensins shows a similar fold and a comparable net positive potential surface. To the best of our knowledge, this is the first report on the structure of a toxin from snake venom active on Na+ channel.

1H5O is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Crotalus_durissus_terrificus Crotalus durissus terrificus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1H5O OCA].  

[[Category: Chiara, C De.]]

[[Category: Giglio, J R.]]

[[Category: Mancin, C A.]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:57:43 2008''