title: Purification and partial amino acid sequences of a new presynaptic toxin and a cytotoxin from venom of pit veper Agkistrodon blomhoffii brevicaudus.
abstract: The technique of the reverse-phase performance liquid chromatography (RP-HPLC) was employed to separate and purify the toxic proteins from the venom of Agkistrodon blomhoffii brevicaudus collected in China. 3 toxic proteins marked as AgTx-1, AgTx-2 and AgTx-3 consisting of about 122 amino acid residues were screened. The toxicities (LD50) of the AgTx-1, AgTx-2 and AgTx-3 were 0.075, 0.51 and 6.6 mg per kg weight of mice respectively. Toxicological experiment in the chick biventer cervicis nerve-muscle preparation showed that the acetylcholine (Ach) sensitivity of the preparation was unchanged after the total failure of the indirect contraction caused by AgTx-1 and AgTx-2, suggesting that they were presynaptic blockers, namely beta-type of snake toxins. However, the amplitude of indirect contraction of the preparation was gradually reduced due to its incomplete relaxation caused by AgTx-3, indicating that it should belong to the category of cytotoxins. The partial amino acid sequences of 3 toxins have been established. It was found in ref. [1] that the sequences of the first 32 N-terminal amino acid residues of AgTx-1 and AgTx-2, as well as beta-agkistrodotoxin (beta-AgTx) reported previously were identical (the residue at the position 30 of beta-AgTx should be Trp). In view of the similarity in toxicities, and the amounts in the venom and other properties, it was concluded that AgTx-1 should be beta-AgTx and consequently was renamed beta 1-AgTx. AgTx-2 should be the isoform of beta 1-AgTx, and correspondingly named beta 2-AgTx.
authors.affiliation: Shanghai Institute of Physiology, Chinese Academy of Sciences.
authors.forename: Y
authors.initials: Y
authors.lastname: Ji
authors.forename: L
authors.initials: L
authors.lastname: Lu
authors.forename: K
authors.initials: K
authors.lastname: Xu
authors.forename: H
authors.initials: H
authors.lastname: Hattori
authors.forename: S
authors.initials: S
authors.lastname: Terakawa
mesh_terms: D017836:Agkistrodon; D000595:Amino Acid Sequence; D000818:Animals; D003435:Crotalid Venoms / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification / Q000633:toxicity; D007928:Lethal Dose 50; D051379:Mice; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects; D009498:Neurotoxins / Q000235:genetics* / Q000302:isolation & purification / Q000633:toxicity; D017729:Presynaptic Terminals / Q000187:drug effects*
chemical_list: C031442:Agkistrodon venoms; D003435:Crotalid Venoms; D009498:Neurotoxins; C070121:beta-agkistrodotoxin