title: Inactivation of toxin B from the Indian cobra by cleavage of a specific bond during limited hydrolysis with trypsin.
abstract: Two neurotoxins, "toxin B", a long neurotoxin from Naja naja, and "cobrotoxin", a short neurotoxin from Naja naja atra, were compared with respect to their limited hydrolysis by trypsin and chymotrypsin and its effect on their neurotoxicity. Limited hydrolysis of toxin B with trypsin cleaves peptide bonds at Arg68-Lys69 and Arg33-Gly34 in the toxin molecule and causes complete loss of the neurotoxicity yielding des-carboxyl terminal toxin B(1-68) nicked at Arg33-Gly34 in the molecule. On the other hand, the des-carboxyl terminal toxin B(1-67) shows 70% of the native toxin B neurotoxicity. These results indicated that the complete loss of the toxicity may be due to hydrolysis of a specific peptide bond, Arg33-Gly34, in the toxin B molecule. Limited trypsin digestion did not affect the toxicity of cobrotoxin and limited chymotrypsin digestion had no effect on either neurotoxin.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002268:Carboxypeptidases; D002918:Chymotrypsin; D004546:Elapid Venoms / Q000378:metabolism*; D006868:Hydrolysis; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000302:isolation & purification; D014357:Trypsin
chemical_list: D004546:Elapid Venoms; D010446:Peptide Fragments; C037375:cobra cytotoxin I; D002268:Carboxypeptidases; D002918:Chymotrypsin; D014357:Trypsin