Some biochemical characteristics and cell membrane actions of a toxic phospholipase A 2 isolated from the venom of the pit viper Agkistrodon Halys (Pallas)

Abstract

M. Jiang, J. Häggblad, E. Heilbronn, B. Rydqvist and D. Eaker. Some biochemical characteristics and cell membrane actions of a toxic phospholipase A 2 isolated from the venom of the pit viper Agkistrodon halys (Pallas). Toxicon 25, 785 – 792, 1987. — A toxic component (AgTx) from the venom of Agkistrodon halys (Pallas) was isolated using DEAE-cellulose DE11 and CM-Sephadex C50 column chromatography and finally purified to homogeneity by FPLC on a MonoQ column. The toxin is a neutral (pI 6.9) single chain polypeptide with a mol. wt of 14,100 and an amino acid composition (123 residues) roughly similar to that of notexin. AgTx was found to have phospholipase A 2 activity which was dependent on calcium and stimulated by sodium deoxycholate. The toxin caused efflux of 2-deoxy-(1- 3H)-glucose-6-phosphate (a cell membrane integrity probe) as well as of [ 3H]acetylcholine from rat brain synaptosomes. No cell membrane damage was induced by AgTx on cultured N1E 115 neuroblastoma cells and chick myotube cultures. The ld 50 ws 150 μg/kg (i.p.) in mice. The main symptom observed was respiratory paralysis. The results obtained show that AgTx can be classified as a toxic phospholipase A 2 with a presynaptic site of action.