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Four neurotoxic polypptidcs were purified from the venom of the South American 'armed' spider Phuncmiu nigrivenrer (Keys) by gel filtration and rcvcrse phase FPLC and HPLC. These cystcine-rich polypcptidcs exhibited dimerent lcvcls of neurotoxicity in mice after intraccrebrovcntricular injection. Tic'-I, TxZ5 and Tx2-6 caused spastic paralysis nnd deuh, 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 (Txl-5). 5291.3 (Tx2-6) and 3742.1 (Tx2-9). The complele amino acid sequences of the neurotoxins were determhxd by automnted Edman degradation and by manual DABITC-PITC microscqeuncc analysis of peptidcs obtained atIer digestions with various proteases. The amino acid sequences ofTx2.1 (53 residue), 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 bad varying seqlxnce identities with other neurotoxins from different spider species and biologiiwlly active peptides from scorpions, a sea snail and seeds of Mirrrliitijufupa.Spider venom; Amino acid xquence; Neuroloxin; Phoneutriu rri~rivwkr

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The first PLA(2) (LsPA-1) from L. stenophrys snake venom was purified to homogeneity using three chromatographic steps and had its complete primary structure determined. An average molecular mass of 13,870.3 kDa was determined by mass spectrometry and a 3.3-fold increase in the PLA(2) activity was observed for LsPA-1 as compared to the whole venom. Multiple alignment of PLA(2) from Lachesis spp. snakes suggested the existence of two geographical clades for this genus in the New World, which is in accordance with morphological, behavioral and mtDNA data obtained by others. Phospholipases A(2) from Crotalus spp. snake venoms were similarly distributed into two groups. Intergroup analysis indicated that most amino acid substitutions were observed in the amino- and carboxy-terminal regions of the molecules in each clade. Both regions have been suggested to play important roles in determining the biological properties of PLA(2) from snake venoms. The dendogram derived for PLA(2) from Lachesis and Crotalus snakes highlighted the phylogenetic relationships between these two genera in the New World.