title: Further evidence showing that neurotoxin-acetylcholine receptor dissociation is accelerated by monoclonal neurotoxin-specific immunoglobulin.
abstract: We have demonstrated that the dissociation of Naja nigricollis alpha-toxin from the two acetylcholine receptor sites [Weber and Changeux, Molec. Pharmac. 10, 1-14 (1974); Rousselet et al., Eur. J. Biochem. 140, 31-37 (1984)], is markedly accelerated by a monoclonal neurotoxin-specific antibody. The dissociation of the toxin occurs in a biphasic manner in the presence of a 900 molar excess of immunoglobulin (with respect to toxin concn). The progress curves are characterized by first-order kinetics. Under these conditions the maximal dissociation rate is achieved as further rate enhancement cannot be induced by exposure to an increased immunoglobulin level. In contrast when a toxin-immunoglobulin complex is incubated with a large excess of receptor, the dissociation kinetics of the complex are not enhanced. The data fit a kinetic model which implicates the existence of a transient ternary complex involving the receptor, the toxin and the antibody.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001667:Binding, Competitive; D003039:Cobra Neurotoxin Proteins / Q000378:metabolism*; D004546:Elapid Venoms / Q000378:metabolism*; D007074:Immunoglobulin G / Q000378:metabolism; D007700:Kinetics; D008954:Models, Biological; D011978:Receptors, Nicotinic / Q000378:metabolism*; D012911:Snakes; D014101:Torpedo
chemical_list: D000911:Antibodies, Monoclonal; D003039:Cobra Neurotoxin Proteins; D004546:Elapid Venoms; D007074:Immunoglobulin G; D011978:Receptors, Nicotinic