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Type: Artigo de periódico
Title: Structure and Activity Analysis of Two Spider Toxins That Alter Sodium Channel Inactivation Kinetics
Author: Matavel, A
Fleury, C
Oliveira, LC
Molina, F
de Lima, ME
Cruz, JS
Cordeiro, MN
Richardson, M
Ramos, CHI
Beirao, PSL
Abstract: In this work, Phoneutria nigriventer toxins PnTx2-5 and PnTx2-6 were shown to markedly delay the fast inactivation kinetics of neuronal-type sodium channels. Furthermore, our data show that they have significant differences in their interaction with the channel. PnTx2-6 has an affinity 6 times higher than that of PnTx2-5, and its effects are not reversible within 10-15 min of washing. PnTx2-6 partially (59%) competes with the scorpion cc-toxin AaHII, but not with the scorpion beta-toxin CssIV, thus suggesting a mode of action similar to that of site 3 toxins. However, PnTx2-6 is not removed by strong depolarizing pulses, as in the known site 3 toxins. We have also established the correct PnTx2-5 amino acid sequence and confirmed the sequence of PnTx2-6, in both cases establishing that the cysteines are in their oxidized form. A structural model of each toxin is proposed. They show structures with poor alpha-helix content. The model is supported by experimental and theoretical tests. A likely binding region on PnTx2-5 and PnTx2-6 is proposed on the basis of their different affinities and sequence differences.
Country: EUA
Editor: Amer Chemical Soc
Citation: Biochemistry. Amer Chemical Soc, v. 48, n. 14, n. 3078, n. 3088, 2009.
Rights: fechado
Identifier DOI: 10.1021/bi802158p
Date Issue: 2009
Appears in Collections:Unicamp - Artigos e Outros Documentos

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