Distinct primary structures of the major peptide toxins from the venom of the spider Macrothele gigas that bind to sites 3 and 4 in the sodium channel

详细信息    查看全文

• 作者：Corzo ; Gerardo ; Gilles ; Nicolas ; Satake ; Honoo ; Villegas ; Elba ; Dai ; Li ; Nakajima ; Terumi ; Haupt ; Joachim
• 关键词：Spider ; Peptide ; Toxin ; Insecticide ; Structure ; Pharmacology ; Ion channel ; TFA ; trifluoroacetic acid ; PC ; protease convertase ; ED₅₀ ; peptide dose that paralyzes 50 % of the animals ; LD₅₀ ; peptide dose that kills 50 % of the animals
• 刊名：FEBS Letters
• 出版年：2003
• 出版时间：July 17, 2003
• 年：2003
• 卷：547
• 期：1-3
• 页码：43-50
• 全文大小：311 K

文摘

Six peptide toxins (Magi 1–6) were isolated from the Hexathelidae spider Macrothele gigas. The amino acid sequences of Magi 1, 2, 5 and 6 have low similarities to the amino acid sequences of known spider toxins. The primary structure of Magi 3 is similar to the structure of the palmitoylated peptide named PlTx-II from the North American spider Plectreurys tristis (Plectreuridae). Moreover, the amino acid sequence of Magi 4, which was revealed by cloning of its cDNA, displays similarities to the Na⁺ channel modifier δ-atracotoxin from the Australian spider Atrax robustus (Hexathelidae). Competitive binding assays using several ¹²⁵I-labelled peptide toxins clearly demonstrated the specific binding affinity of Magi 1–5 to site 3 of the insect sodium channel and also that of Magi 5 to site 4 of the rat sodium channel. Only Magi 6 did not compete with the scorpion toxin LqhαIT in binding to site 3 despite high toxicity on lepidoptera larvae of 3.1 nmol/g. The K_is of other toxins were between 50 pM for Magi 4 and 1747 nM for Magi 1. In addition, only Magi 5 binds to both site 3 in insects (K_i