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- Title
Sequence and structure‐activity relationship of a scorpion venom toxin with nitrergic activity in rabbit corpus cavernosum.
- Authors
Teixeira, Cleber E.; Ifa, Demian R.; Corsoi, Gaetano; Santagada, Vincenzo; Caliendo, Giuseppe; Antunes, Edson; De Nucci, Gilberto
- Abstract
An α‐toxin responsible for nitric oxide (NO) release in rabbit corpus cavernosum (RbCC) was isolated from Tityus serrulatus venom (TSV). The isolated peptide (molecular mass of 7427.66±0.15 Da) was identified as Ts3 after determination of Cys residues, N‐terminal amino acid analysis, and proteolytic peptide mapping. Ts3 (30 nM) markedly relaxed the RbCC; this response was blocked by the NO synthesis inhibitor Nω‐nitro‐L‐arginine methyl ester (100 μM) and the Na+ channel blocker tetrodotoxin (100 nM). Synthetic peptides based on either Ts3 (P1–16, p17–32, p33–48, p49–64, p9–24, p25–40, p41–56, YGLPDKVPTKT) or Bukatoxin (isolated from Buthus martensi Karsch scorpion venom) sequence (Buka11, Buka11‐B, PDKVP, PDSEP) were assayed. These peptides slightly relaxed the RbCC, and such an effect was independent of Na+ channel activation or NO release. Our results indicate that Ts3 exerts nitrergic actions and contributes to the relaxing activity of TSV in RbCC, thus providing a valuable tool to investigate the mechanisms underlying nerve activation in erectile tissues, because NO released from nitrergic fibers plays a key role in the erectile process. Our findings revealed the key importance of the Ts3 structure three‐dimensional conformation maintenance for biological activity, because linear peptide sequences neither presented substantial relaxations nor was this effect related to nitrergic activity.
- Publication
FASEB Journal, 2003, Vol 17, Issue 3, p1
- ISSN
0892-6638
- Publication type
Article
- DOI
10.1096/fj.02-0635fje