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Novel K(+)-channel-blocking toxins from the venom of the scorpion Centruroides limpidus limpidus Karsch.
Martin, B M; Ramirez, A N; Gurrola, G B; Nobile, M; Prestipino, G; Possani, L D.
Afiliación
  • Martin BM; National Institute of Mental Health, Molecular Neurogenetics Unit, Bethesda, MD 20892.
Biochem J ; 304 ( Pt 1): 51-6, 1994 Nov 15.
Article en En | MEDLINE | ID: mdl-7998956
Two novel toxins were purified from the venom of the Mexican scorpion Centruroides limpidus limpidus, using an immunoassay based on antibodies raised against noxiustoxin (NTX), a known K(+)-channel-blocker-peptide. The primary structure of C. l. limpidus toxin 1 was obtained by Edman degradation and was shown to be composed of 38 amino acid residues, containing six half-cystines. The first 36 residues of C. l. limpidus toxin 2 were also determined. Both toxins are capable of displacing the binding of radio-labelled NTX to rat brain synaptosomes with high affinity (about 100 pM). These toxins are capable of inhibiting transient K(+)-currents (resembling IA-type currents), in cultured rat cerebellar granule cells. About 50% of the peak currents are reduced by application of a 1.5 microM solution of toxins 1 and 2 The K+ current reduction is partially reversible, under washing but not voltage-dependent. Comparison of the primary structure of C. l. limpidus toxin 1 with other known toxins shows 74% identity with margatoxin, 64% with NTX, 51% with kaliotoxin, 39% with iberiotoxin, 37% with charybdotoxin and Lq2, and 29% with leirutoxin 1. The only invariant amino acids in all these toxins are the six cysteines, a glycine in position 26 and two lysines at positions 28 and 33, respectively. The relevance of these differences in terms of possible structure-function relationships is discussed.
Asunto(s)

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Venenos de Escorpión / Toxinas Biológicas / Bloqueadores de los Canales de Potasio Límite: Animals Idioma: En Revista: Biochem J Año: 1994 Tipo del documento: Article Pais de publicación: Reino Unido

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Venenos de Escorpión / Toxinas Biológicas / Bloqueadores de los Canales de Potasio Límite: Animals Idioma: En Revista: Biochem J Año: 1994 Tipo del documento: Article Pais de publicación: Reino Unido