title: beta-Bungarotoxin. The binding of [3H]pyridoxylated beta-bungarotoxin to a high-molecular-weight protein receptor.
abstract: beta-Bungarotoxin was labelled with pyridoxal 5'-phosphate (incorporating 3H). The kinetics of beta-bungarotoxin binding to several tissue subfragments of nervous tissue was studied. The dissociation constant of 3H-pyridoxylated beta-bungarotoxin in this reaction was 0.21-0.37 micron and that of unlabelled beta-bungarotoxin was 25 nM. Hill [(1910) J. Physiol. (London) 40, iv-vii] and Scatchard [(1949) Ann. N.Y. Acad. Sci. 51, 660-672] analyses demonstrated no co-operativity of binding and only a single class of receptor sites, consistent with a bimolecular association of beta-bungarotoxin and its receptor. The iodinated toxin was physiologically inactive. Toxin was bound in non-specific unsaturable fashion by glass and/or plastic. This low-affinity binding was corrected by addition of bovine serum albumin to a final concentration of 30 mg/ml. A soluble protein receptor of beta-bungarotoxin was isolated and the mol.wt. is approx. 200000.
mesh_terms: D000818:Animals; D002038:Bungarotoxins / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008970:Molecular Weight; D051381:Rats; D011955:Receptors, Drug / Q000302:isolation & purification / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D002038:Bungarotoxins; D011955:Receptors, Drug