Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1573-9023
    Keywords: dipole moment ; neurotoxin ; NMR ; potassium channel ; scorpion ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Scorpion venom contains various toxins which block ion-channels, responsible for either sodium, potassium, calcium or chloride membrane permeation. This review focuses on the three-dimensional structure of scorpion toxins specific for potassium channels, and on their structure–activity relationships. The overall fold of all these toxins is similar, despite their various specificities towards different types of potassium channels. Fine studies of the influence of punctual mutations of both toxins and channels have converged on a precise description of the scorpion toxins functional maps. From this knowledge, it now becomes possible to predict the specificity of a newly described scorpion toxin. The way is thus now open that leads to the design of new potent synthetic potassium channel blockers which in turn could be used as therapeutic drugs.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0887-3585
    Keywords: scorpion venom ; neurotoxin ; NMR ; structure-activity relationships ; calcium activated-potassium channel ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The venom of the North African scorpion Androctonus mauretanicus mauretanicus possesses numerous highly active neurotoxins that specifically bind to various ion channels. One of these, P05, has been found to bind specifically to calcium-activated potassium channels and also to compete with apamin, a toxin extracted from bee venom. Besides the highly potent ones, several of these peptides (including that of P01) have been purified and been found to possess only a very weak, although significant, activity in competition with apamin. The amino acid sequence of P01 shows that it is shorter than P05 by two residues. This deletion occurs within an α-helix stretch (residues 5-12). This α-helix has been shown to be involved in the interaction of P05 with its receptor via two arginine residues. These two arginines are absent in the P01 sequence. Furthermore, a proline residue in position 7 of the P01 sequence may act as an α-helix breaker. We have determined the solution structure of P01 by conventional two-dimensional 1H nuclear magnetic resonance and show that 1) the proline residue does not disturb the α-helix running from residues 5 to 12; 2) the two arginines are topologically replaced by two acidic residues, which explains the drop in activity; 3) the residual binding activity may be due to the histidine residue in position 9; and 4) the overall secondary structure is conserved, i.e., an α-helix running from residues 5 to 12, two antiparallel stretches of β-sheet (residues 15-20 and 23-27) connected by a type I′ β-turn, and three disulfide bridges connecting the α-helix to the β-sheet.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0887-3585
    Keywords: scorpion neurotoxin ; NMR ; structure ; potassium channel ; maurotoxin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Maurotoxin (MTX), purified from the scorpionid Scorpio maurus is a potent ligand for potassium channels. It shows a broad specificity as being active on Kv1.1 (Kd = 37 nM), Kv1.2 (Kd = 0.8 nM), Kv1.3 (Kd = 150 nM) voltage-gated potassium channels, as well as on small-conductance calcium-activated potassium channels. It has a unique disulfide pairing among the scorpion toxins family. The solution structure of MTX has been determined by 2D-NMR techniques, which led to the full description of its 3D conformation: a bended helix from residues 6 to 16 connected by a loop to a two-stranded antiparallel β sheet (residues 23 to 26 and 28 to 31). The interaction of MTX with the pore region of the Kv1.2 potassium channel has been modeled according to their charge anisotropy. The structure of MTX is similar to other short scorpion toxins despite its peculiar disulfide pairing. Its interaction with the Kv1.2 channel involves a dipole moment, which guides and orients the toxin onto the pore, toward the binding site, and which thus is responsible for the specificity. Proteins 29:321-333, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0887-3585
    Keywords: scorpion ; neurotoxin ; NMR ; structure ; small conductance potassium channel ; Tityus serrulatus ; TsKapa ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: TsKapa (TsK), purified from the Buthidae Tityus serrulatus is a very high potent ligand for small-conductance apamin-sensitive calcium-activated potassium channels (SK). It is able to efficiently compete with apamin for binding on this channel (K0.5 = 0.3 nM) [Legros, C. et al., FEBS Lett. 390:81-84, 1996]. The solution structure of TsK has been determined by 2D-NMR techniques, which led to the full description of its 3D conformation: a short α helix from residues 14 to 20 and a three-stranded antiparallel β sheet (residues 2-3, 27-29, and 32-34). The interaction of TsK with the SK potassium channel has been modeled according to the charge anisotropy of the ligand. The resulting dipole moment orientates TsK so that it presents toward the receptor, a surface, mainly basic, encompassing residues K18 and K19 on one side and R9 and Y8 on the other. Despite its three-dimensional structure that is related with scorpion toxins active on voltage-gated potassium channels such as charybdotoxin, the pharmacological activity and specificity of TsK is related with shorter scorpion toxins (i.e., possessing an only two-stranded β sheet) such as scyllatoxin (also named leiurotoxin I) or P05. Proteins 29:359-369, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...