title: Comparison of the binding characteristics of two different preparations of tetanus toxin to rat brain membranes.
abstract: Two different preparations of tetanus toxin (HTT and WTT) were iodinated, and their binding to rat brain membranes characterized. Under optimal binding conditions (25 mM Tris-acetate, pH 6.0), both preparations bound to a large number of high affinity sites, thought to be gangliosides. Binding constants were identical. However, in a physiological buffer (Krebs-Ringer, pH 7.4) binding of the two toxin preparations showed a number of differences. Under these conditions we have previously shown that HTT binding is markedly reduced, and that there are two classes of sites, a small number of heat-, sialidase- and protease-sensitive high affinity sites, and a larger number of sialidase-sensitive, heat- and protease-resistant lower affinity sites, probably gangliosides (PIERCE et al. (1986) Biochem. J. 236, 845-852). Although WTT bound to these same two sites, it displayed a higher affinity for the protease-resistant site than did HTT. WTT also bound to free or immobilized trisialoganglioside with higher affinity than HTT, consistent with the view that the protease-resistant site represents binding to ganglioside. In contrast, both toxin preparations bound to the protease-sensitive site with similar affinities. These observations may explain the four to five-fold higher levels of WTT binding to brain membranes, and the fact that a smaller percentage of total WTT binding is protease sensitive. Despite their different ganglioside-binding properties, both toxin preparations showed comparable neurotoxic activities, and appeared identical on SDS gels.
authors.affiliation: Department of Biochemistry, University of Leicester, U.K.
authors.forename: R G
authors.initials: RG
authors.lastname: Parton
authors.forename: M D
authors.initials: MD
authors.lastname: Davison
authors.forename: D R
authors.initials: DR
authors.lastname: Critchley
mesh_terms: D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D005732:Gangliosides / Q000494:pharmacology; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D008566:Membranes / Q000378:metabolism; D009498:Neurotoxins / Q000633:toxicity; D051381:Rats; D011919:Rats, Inbred Strains; D013744:Tetanus Toxin / Q000378:metabolism*
chemical_list: D005732:Gangliosides; D007457:Iodine Radioisotopes; D009498:Neurotoxins; D013744:Tetanus Toxin; C016806:trisialoganglioside