title: The neutralization mechanism of Vipera palaestinae neurotoxin by a purified factor from homologous serum.
abstract: The serum of Vipera palaestinae contains two separate factors which neutralize the hemorrhagic and the neurotoxic activities of its venom. The purified antineurotoxic factor shows one major band in disc electrophoresis and an 800-fold increase in specific activity. Its molecular weight is approximately 56 000 and the isoelectric point is 4.0. These data, together with the failure to form precipitin lines in immuno-diffusion tests, suggest that the antineurotoxic factor of Vipera palaestinae serum is probably an albumin-like or alpha-globulin fraction rather than an immunoglobulin fraction. In vivo experiments show that the neutralizing protein does not protect or block the neurotoxin target sites. When the  neurotoxic fraction is injected into mice intravenously at different intervals following injection of the snake serum, the neutralizing activity decreases with time. Experiments carried out in vitro show that the antineurotoxic factor is inactivated upon heating at 95 degrees C for 10 min but resists boiling when mixed with the neurotoxic component, suggesting the formation of a thermostable complex between the two components. This assumed complex dissociates at pH 2.5 and the neurotoxic activity reappears. Further investigation of the reaction with 131I-labeled neurotoxin and neurotoxin components shows that a stable complex is formed between the neutralizing protein and one of the synergistic components of the neurotoxic fraction.
mesh_terms: D000818:Animals; D001681:Biological Assay; D001798:Blood Proteins / Q000302:isolation & purification; D051379:Mice; D008970:Molecular Weight; D009420:Nervous System / Q000187:drug effects; D010525:Peripheral Nerves / Q000187:drug effects; D012867:Skin / Q000187:drug effects; D012910:Snake Venoms / Q000302:isolation & purification / Q000494:pharmacology; D012911:Snakes / Q000097:blood*; D014118:Toxins, Biological / Q000494:pharmacology
chemical_list: D001798:Blood Proteins; D012910:Snake Venoms; D014118:Toxins, Biological