title: Mapping of an epitope recognized by a neutralizing monoclonal antibody specific to toxin Cn2 from the scorpion Centruroides noxius, using discontinuous synthetic peptides.
abstract: The Na+-channel-affecting toxin Cn2 represents the major and one of the most toxic components of the venom of the Mexican scorpion Centruroides noxius Hoffmann. A monoclonal antibody BCF2 raised against Cn2 has been shown previously to be able to neutralize the toxic effect of Cn2 and of the whole venom of C. noxius. In the present study the epitope was mapped to a surface region comprising the N- and C-terminal segments of Cn2, using continuous and discontinuous synthetic peptides, designed on the basis of the sequence and a three-dimensional model of Cn2. The study of peptides of varying length resulted in the identification of segments 5-14 and 56-65 containing residues essential for recognition by BCF2. The peptide (abbreviated SP7) with the highest affinity to BCF2 (IC50 = 5.1 microM) was a synthetic heterodimer comprising the amino acid sequence from position 3-15 (amidated) of Cn2, bridged by disulfide to peptide from position 54-66, acetylated and amidated. Similar affinity was found with peptide SP1 [heterodimer comprising residues 1-14 (amidated) of Cn2, bridged with synthetic peptide 52-66 (acetylated)]. SP1 and SP7 were used to induce anti-peptide antibodies in mouse and rabbit. Both peptides were highly immunogenic. The sera obtained were able to recognize Cn2 and to neutralize Cn2 in vitro. The most efficient protection (8.3 microgram Cn2 neutralized per mL of serum) was induced by rabbit anti-SP1 serum.
authors.affiliation: Department of Molecular Recognition, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico.
authors.forename: E S
authors.initials: ES
authors.lastname: Calderon-Aranda
authors.forename: B
authors.initials: B
authors.lastname: Selisko
authors.forename: E J
authors.initials: EJ
authors.lastname: York
authors.forename: G B
authors.initials: GB
authors.lastname: Gurrola
authors.forename: J M
authors.initials: JM
authors.lastname: Stewart
authors.forename: L D
authors.initials: LD
authors.lastname: Possani
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D018604:Epitope Mapping; D005260:Female; D006801:Humans; D007114:Immunization; D066298:In Vitro Techniques; D007928:Lethal Dose 50; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D010446:Peptide Fragments / Q000235:genetics / Q000276:immunology; D011487:Protein Conformation; D011817:Rabbits; D012604:Scorpion Venoms / Q000235:genetics / Q000276:immunology* / Q000633:toxicity; D012605:Scorpions / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D015222:Sodium Channels / Q000187:drug effects
chemical_list: D000911:Antibodies, Monoclonal; D010446:Peptide Fragments; D012604:Scorpion Venoms; D015222:Sodium Channels