Toxins action

Published data (2) on allelcpathic agents, however, indicate that the following parameters affect the grcwth process due to toxin action ... 

The latter problems are of particular interest to chemists, who should devise appropriate methods for resolving the complexity of chemicals, properly identifying them and finally determining their exact composition and makeup. The participation of chemists is needed to verify the concept of allelopathy as a concentration-dependent phenomenon. They should help to reconstitute the chemical composition as it was found in the original and isolated plant samples. This systematic approach leads to verification of the concept as well as to proper assessment of the initial observation with crude extracts, and to final application to the field situation. Once the concept is proven, same simulation experiments need to be performed to maximize the allelopathic effect (toxin action). The concentration of the toxic chemicals is varied to where the threshold levels of chemicals prove to be involved in the exhibition of allelopathy under field conditions. 

SEA, SEE, and SED require zinc binding to MHC class II. Binding of SEC3 also needs zinc, but is performed by different mechanisms than in SEA and SEE. Toxin has a structure (H-E-x-x-H) similar to metalloenzymes, e.g., thermilysin (Hase and Finkelstein,1993). Similar structures were identified in botulin neurotoxin. The toxin reveals proteolytic activity, which has a fundamental significance for the mode of toxin action (Papageorgiou et ah, 1995). 

Channel Types Mode of Toxin Action Source... 

Goodman Gilman s The Pharmacological Basis of Therapeutics. New York McGraw Hill, 2005. Simpson LL. Identification of the major steps in botulinum toxin action. Ann Rev Pharmacol Toxicol 2004 44 167-193. 

Frasson E, Priori A, Ruzzante B, et al. Nerve stimulation boosts botulinum toxin action in spasticity. Mov Disord. 2005 20 624-629. 

Scheer H, Prestipino G, Meldolesi J (1986) Reconstitution of the purified a-latrotoxin receptor in liposomes and planar lipid membranes. Clues to the mechanism of toxin action. EMBO J 5 2643-8... 

Got subunits of the Gi/o type of G proteins can be ADP-ribosylated in the presence of pertussis toxin at Cys351, four amino acids from the C-terminus. Petussis toxin sensitivity is the major method of identifying a role for Gai/o proteins in GPCR-mediated signaling. This treatment prevents receptor-mediated G-protein activation and thus exchange of GTP for GDP and so blocks signaling by Ga and G(3y. There are numerous examples of the use of this technique to identify coupling of the delta opioid receptor [e.g., 2,3,41,42,73,77]. One Ga protein in this class, Gaz, lacks the Cys residue that is the site for pertussis toxin action and so is insensitive to pertussis toxin treatment [see 17 for review]. 

Advantages of the Mouse Hemidiaphragm Assay Current approaehes to the inhibition of BoNT activity involve a number of strategies, eaeh with potential advantages and disadvantages. Ultimately, model test systems that can incorporate eaeh of these potential approaches are needed to evaluate the relative merit of potential therapeutic compounds. Since the presynaptic terminal is the primary target for BoNTs, a test system based on toxin action at... 

Simpson, L.L. (2004). Identification of the major steps in hotulinum toxin action, Rev. Pharmacol. Toxicol. 44 167-93. 

Cassel D, PfeufferT (1978) Mechanism of cholera toxin action covalent modification of the guanyl nucleotide-binding protein of the adenylate cyclase system. In Proc, Natl. Acad. Sc/. (USA) 75 2669-2673... 

Jakobs KH, Aktories K, Schultz G (1984) Mechanism of pertussis toxin action on the adenylate system inhibition of the turn-on reaction of the inhibitory regulatory site. In Eur. J. Biochem. 140 177-181... 

In the following paragraphs, we will first briefly review the mechanism of action of these toxins (for a more comprehensive discussion see this volume. Chapter 14 Montecucco and Schiavo, 1994, Niemann et ai, 1994). We will then give a short overview over the preparations that have been used in the study of toxin action. Finally, we will describe in detail the procedures required for the study of these toxins using isolated nerve terminals (synaptosomes) as an experimental model system. 

Link E, Edelmann L, Chou et al. (1992) Tetanus toxin action inhibition of neurotransmitter release linked to synaptobrevin proteolysis. Biochem. Biophys. Res. Comm. 189 1017-23. 

Singh Y, Chaudhary VK, Leppla SH (1989) A deleted variant of Bacillus anthracis protective antigen is non-toxic and blocks anthrax toxin action in vitro. J Biol Cbem 264 19103-19107. 

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