Author/Editor		Križaj, Igor; Faure, Grazyna; Gubenšek, Franc; Bon, Cassian
Title		Re-examination of crotoxin-membrane interactions
Type		članek
Source		Toxicon
Vol. and No.		Letnik 34, št. 9
Publication year		1996
Volume		str. 1003-9
Language		eng
Abstract		The interaction of crotoxin with synaptic membranes from Torpedo marmorata has been re-examined, using radioiodinated toxin. In competition experiments, the 'saturble binding' is usually calculated by subtracting the non-saturable binding, determined in the presence of an excess of unlabelled crotixin, from total binding. Paradoxically, we observed a notable increase of the 'saturable binding' of 125I-crotoxin, defined inthis manner in the presence of a high concentration of certain competitors (e.g. crotoxin subunit B, akgistrodoxin, ammodytoxin and ammodytin I2). This potentiation effect was analysed by competition and cross-linking experiments. The dissociation of the basic crotoxinsubunit CB, which differs markedly from crotoxin in its membrane- binding characteristics, was found to be the main reason for the observed phenomenon. 125I-CB could be released from 125I-crotoxin by exchange with a molecule having sufficient affinity towards CA (e.g. CB or agkistrodotoxin) or it could be dissociated from the specific crotoxin membrane-binding site(s) by a competitot molecule. Our results, therefore, suggest a reinterpretation of previous 125I-crotoxin binding studies.
Descriptors		CROTALID VENOMS CROTOXIN SYNAPTIC MEMBRANES BINDING, COMPETITIVE CROSS-LINKING REAGENTS ELECTROPHORESIS, POLYACRYLAMIDE GEL IODINE RADIOISOTOPES ISOTOPE LABELING RADIOLIGAND ASSAY TORPEDO