title: The purification and amino acid sequences of four Tx2 neurotoxins from the venom of the Brazilian 'armed' spider Phoneutria nigriventer (Keys).
abstract: Four neurotoxic polypeptides (Tx2-1, Txt2-5, Tx2-6 and Tx2-9) were purified from the venom of the South American 'armed' spider Phoneutria nigriventer (Keys) by gel filtration and reverse phase FPLC and HPLC. These cysteine-rich polypeptides exhibited different levels of neurotoxicity in mice after intracerebroventricular injection. Tx2-1, Tx2-5 and Tx2-6 caused spastic paralysis and death, but the less toxic Tx2-9 produced only tail erection and scratching. The molecular weights of the polypeptides as determined by desorption mass spectroscoopy were 5838.8 for Tx2-1, 5116.6 (Tx2-5), 5291.3 (Tx2-6) and 3742.1 (Tx2-9). The complete amino acid sequences of the neurotoxins were determined by automated Edman degradation and by manual DABITC-PITC microsequence analysis of peptides obtained after digestions with various proteases. The amino acid sequences of Tx2-1 (53 residues), Tx2-5 (49 residues) and Tx2-6 (48 residues) were homologous, but had only limited similarities to the less toxic Tx2-9 (32 residues). All four polypeptides had varying sequence identities with other neurotoxins from different spider species and biologically active peptides from scorpions, a sea snail and seeds of Mirabilis jalapa.
authors.affiliation: Centro de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Belo Horizonte (MG), Brazil.
authors.forename: M do N
authors.initials: Mdo N
authors.lastname: Cordeiro
authors.forename: C R
authors.initials: CR
authors.lastname: Diniz
authors.forename: A do C
authors.initials: Ado C
authors.lastname: Valentim
authors.forename: V R
authors.initials: VR
authors.lastname: von Eickstedt
authors.forename: J
authors.initials: J
authors.lastname: Gilroy
authors.forename: M
authors.initials: M
authors.lastname: Richardson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D006168:Guinea Pigs; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000187:drug effects; D009479:Neuropeptides / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity; D009498:Neurotoxins / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity; D017385:Sequence Homology; D012689:Sequence Homology, Nucleic Acid; D013111:Spider Venoms / Q000737:chemistry* / Q000633:toxicity
chemical_list: D009479:Neuropeptides; D009498:Neurotoxins; D013111:Spider Venoms; C076902:Tx2 neurotoxin