Immunochemistry of apamin—bee venom neurotoxin—I. Radioimmunoassay with apamin and its derivatives

Abstract Antibodies against apamin, a neurotoxic polypeptide from bee venom were raised in rabbits by immunization with apamin or apamin-BSA conjugates. 3 H-apamin or 125 I-apamin were used in radioimmunoassay with anti-apamin for the detection of the apamin antigenic site. The inhibitory activity toward the labelled apamin-anti-apamin binding was maximal with unlabelled apamin and decreased in the range: apamin > Cys 1 , Lys 4 -disuccinilated apamin > Cys 1 , Lys 4 -diacetylated apamin > Cys 1 , Lys 4 -diacetylated apamin with carboxymethylated His 18 . Dipyrimidyl-Orn 13 ,Orn 14 -apamin derivative almost had no inhibitory activity on labelled apamin binding emphasizing that Arg 13 , Arg 14 are the most essential for the apamin topographic antigenic site.