Biosensor binding assay of BmK AS-1, a novel Na+ channel-blocking scorpion ligand on rat brain synaptosomes.
The pharmacological binding of BmK AS-1, a novel Na+ channel-specific ligand purified from Chinese scorpion Buthus martensi Karsch (BmK), has been investigated by biosensor assay. The results showed a fast association rate constant (1.14 x 10(4) M(-1) s(-1)) but a very slow dissociation rate constant (3.24 x 10(-5) s(-1)) for BmK AS-1 binding to the Na+ channel on rat brain synaptosomes. The binding of BmK AS-1 to rat brain synaptosomes could be partially competed by BmK IT2, a depressant insect-selective toxin, but not by BmK I, an alpha-like toxin from the same venom. It was thus further demonstrated that BmK AS-1 might bind to a distinct receptor site, which was partially overlapping that for BmK IT2, but different from that of BmK I on rat brain Na+ channels.
Jia
L Y
LY
Shanghai Institute of Physiology, Chinese Academy of Sciences, Shanghai Research Center of Life Sciences, People's Republic of China.
Zhang
J W
JW
Ji
Y H
YH
D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D015374:Biosensing Techniques; D001923:Brain Chemistry / Q000187:drug effects*; D066298:In Vitro Techniques; D007700:Kinetics; D008024:Ligands; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D012604:Scorpion Venoms / Q000494:pharmacology*; D026941:Sodium Channel Blockers; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
C119408:KAS-1 toxin, Buthus martensi; D008024:Ligands; D010455:Peptides; D012604:Scorpion Venoms; D026941:Sodium Channel Blockers