Dyskusja:Mamba
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FASCICULINE - tak po ang. sie nazywa ta neurotoksycna którą ma czarna mamba, ale nie wiem jak to przetłumaczyc...
ja nie jestem od węży tylko od chemii, tu jest tekst w któþrym jest wszystko o toksynach mamby:
Structurally, muscarinic toxins are similar to other members of the large group of 3FTx (three-finger toxins) such as alpha-neurotoxins, fasciculins, calciseptines, mambins and cardiotoxins/cytotoxins but are more variable in primary structure. The higher degree of variability amongst muscarinic toxins than amongst comparable alpha-neurotoxins is not surprising as these toxins target five different receptors versus the two targeted by the alpha-neurotoxins.
Due to specificity of binding, muscarinic toxins have shown to be useful in the characterization of receptor sub-types found in particular tissues. MT-3, as a case point, was shown to be a potent yet reversible competitive antagonist at the M4 subtype muscarinic receptor. This toxin was used to identify the presence of M4 receptors in the rat brain through the selective inhibition of adenylate cyclase activity. Similarly, M1 toxins were used to bind the M1 receptor on rat striated muscle tissue and M4-specific toxins were used to show that M4 subtype muscarinic receptors make up the vast majority of the remaining receptors. These receptors are of great interest in the treatment of Parkinson's disease, as it is hoped that selectively blocking the M4 receptors would greatly aid in restoring normal movement.
Other toxins have been shown to inhibit the binding of muscarinic ligands, specifically a 13,600 MW component from Naja sputatrix and a 13,800 MW component from Crotalus atrox. However, rather than being peptides such as in the mamba muscarinic toxins, these components are larger phospholipase A2(PLA2) enzymes. These toxins were significantly less potent than those isolated from the mambas and displayed none of the useful specificity.
Dendrotoxins The mambas are quite unique amongst the elapids in possessing a class of toxins, the dendrotoxins, which are active upon voltage gated potassium channels. Dendrotoxins are approximately 59 amino acid single chain peptides with three disulfide bonds and are part of the snake toxin family that utilises the BPTI/Kunitz-type protease inhibitor scaffold. A structural key to the differentiation between the potassium channel blocking dendrotoxins and the protease inhibiting toxins is the Lys 5 residue of the dendrotoxins lying in close association with a hydrophobic residue (Leu, Tyr or Phe 9).
Through the use of a dendrotoxin as an investigational tool, a new class of potassium channel toxin was discovered in sea anemone venom. As a number of invertebrate toxins such as those from scorpions also target the same sight but the toxins are structurally distinct, this allows the use of the toxins as investigational ligands of receptor binding sites. Koń 16:22, 13 sie 2004 (CEST)
