Chemical modification of taipoxin and the consequences for phospholipase activity, pathophysiology, and inhibition of high-affinity choline uptake.
Treatment of taipoxin with p-bromophenacyl bromide resulted in modification of single histidine residues in the alpha and beta subunits. The modification decreased the neurotoxicity (lethality) 350-fold, but the inhibitory action on high-affinity choline transport was reduced only threefold. The phospholipase activity and Ca2+-association constants for taipoxin and its subunits were determined. A model for the neurotoxicity of taipoxin indicates the alpha subunit as the ultimate cause of the disruption of synaptic transmission.
D000098:Acetophenones; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000648:ultrastructure; D002118:Calcium; D002794:Choline / Q000378:metabolism; D002942:Circular Dichroism; D004546:Elapid Venoms / Q000494:pharmacology; D004557:Electric Organ / Q000187:drug effects / Q000378:metabolism; D005399:Fishes; D006639:Histidine; D008297:Male; D051379:Mice; D009466:Neuromuscular Blocking Agents / Q000494:pharmacology; D009469:Neuromuscular Junction / Q000187:drug effects; D010740:Phospholipases / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation
D000098:Acetophenones; D004546:Elapid Venoms; D009466:Neuromuscular Blocking Agents; D006639:Histidine; C015523:taipoxin; D010740:Phospholipases; D002794:Choline; C006821:4-bromophenacyl bromide; D002118:Calcium