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Azemiopsin from Azemiops feae viper venom, a novel polypeptide ligand of nicotinic acetylcholine receptor.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2012 Aug 03; Vol. 287 (32), pp. 27079-86. Date of Electronic Publication: 2012 May 21. - Publication Year :
- 2012
-
Abstract
- Azemiopsin, a novel polypeptide, was isolated from the Azemiops feae viper venom by combination of gel filtration and reverse-phase HPLC. Its amino acid sequence (DNWWPKPPHQGPRPPRPRPKP) was determined by means of Edman degradation and mass spectrometry. It consists of 21 residues and, unlike similar venom isolates, does not contain cysteine residues. According to circular dichroism measurements, this peptide adopts a β-structure. Peptide synthesis was used to verify the determined sequence and to prepare peptide in sufficient amounts to study its biological activity. Azemiopsin efficiently competed with α-bungarotoxin for binding to Torpedo nicotinic acetylcholine receptor (nAChR) (IC(50) 0.18 ± 0.03 μm) and with lower efficiency to human α7 nAChR (IC(50) 22 ± 2 μm). It dose-dependently blocked acetylcholine-induced currents in Xenopus oocytes heterologously expressing human muscle-type nAChR and was more potent against the adult form (α1β1εδ) than the fetal form (α1β1γδ), EC(50) being 0.44 ± 0.1 μm and 1.56 ± 0.37 μm, respectively. The peptide had no effect on GABA(A) (α1β3γ2 or α2β3γ2) receptors at a concentration up to 100 μm or on 5-HT(3) receptors at a concentration up to 10 μm. Ala scanning showed that amino acid residues at positions 3-6, 8-11, and 13-14 are essential for binding to Torpedo nAChR. In biological activity azemiopsin resembles waglerin, a disulfide-containing peptide from the Tropidechis wagleri venom, shares with it a homologous C-terminal hexapeptide, but is the first natural toxin that blocks nAChRs and does not possess disulfide bridges.
- Subjects :
- Amino Acid Sequence
Animals
Chromatography, High Pressure Liquid
Circular Dichroism
Ligands
Male
Mice
Mice, Inbred BALB C
Molecular Sequence Data
Peptides chemistry
Peptides metabolism
Sequence Homology, Amino Acid
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Viper Venoms metabolism
Viper Venoms pharmacology
Peptides pharmacology
Receptors, Nicotinic metabolism
Viper Venoms chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1083-351X
- Volume :
- 287
- Issue :
- 32
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 22613724
- Full Text :
- https://doi.org/10.1074/jbc.M112.363051