Purification and amino acid sequences of six Tx3 type neurotoxins from the venom of the Brazilian ‘armed’ spider Phoneutria Nigriventer (keys.)

Abstract

Six neurotoxic peptides (Tx3-1 to Tx3-6) were purified from the venom of the spider Phoneutria nigriventer by a combination of gel filtration, reverse phase FPLC on PEP-RPC and PRO-RPC columns, reverse phase HPLC on Vydac C18, and ion exchange HPLC on cationic and anionic columns. These toxins caused different neurological symptoms in mice after intracerebro-ventricular injection. At dose levels of 5 μg/mouse, Tx3-3 and Tx3-4 caused rapid general flaccid paralysis followed by death in 10–30 min; Tx3-2 induced immediate clockwise gyration and flaccid paralysis after 6 hr; Tx3-1, Tx3-5 and Tx3-6 produced paralysis only in the posterior limbs and gradual decreases in movement and aggression during 24 hr. The mol. wt of these cystine-rich peptides were found to be in the range of 3500–8500 by mass spectroscopy and SDS-PAGE. The complete amino acid sequences of the neurotoxins Tx3-1 (40 residues), Tx3-2 (34 residues) and Tx3-6 (55 residues), and the N-terminal sequences of Tx3-3 (34 res.), Tx3-4 (40 res.) and Tx3-5 (36 res.) were established by direct automated Edman degradation, and manual DABITC/PITC microsequence analyses of peptides obtained from digests with various proteases. The structures of these Tx3 neurotoxins from Phoneutria nigriventer exhibited sequence similarities to one another and to the neurotoxins from the venoms of the spiders Hololena curta and Agelenopsis aperta, which were most evident in the location of the Cys residues.