Charybdotoxin 4-

Charlie CHARMm Charpy Izod impact Charpy method Charpy test CHARTEK59 Charybdotoxin Chaser mill Chatecholates... 

Big-conductance Ca2+ sensitive K+ (BKca) channels are activated by calcium surge and membrane depolarization. BKCa channels are specifically blocked by iberiotoxin and less selectively by charybdotoxin. BKCa channels are composed of pore-forming a and auxiliary (3 subunits. Both BKCa,a andBKca, 3 subunits as well as their efficient coupling in the heteromultimeiic formation of BKca channel complexes are important for the function of BKCa channels. 

BKCa- P4 KCNMB4 12q14.1-q15 Brain, heart, kidney BKca Iberiotoxin-, charybdotoxin-resistant ... 

Sanders That preparation has a resting potential of — 65 mV. If you add charybdotoxin to that tissue you are not going to depolarize it because there are very few BK channels being activated. 

The three-dimensional structural architecture of plant defensins is exemplified by the structure of Rs-AFP, ° which comprises an N-terminal /3-strand followed by an ct-helix and two /3-strands (/3a/3/3 configuration). The /3-strands form a triple-stranded antiparallel /3-sheet. The three-dimensional structure is stabilized by three disulfide bonds. In general, in plant defensins two disulfide bonds form between the ct-helix and the central /3-strand. A third disulfide bond stabilizes the structure by linking the /3-strand after the helix to the coiled part after the ct-helix. This motif is called the cysteine-stabilized a/3-motif (CSa/3)" and also occurs in toxins isolated from insects, spiders, and scorpions.The fourth disulfide bond links the C-terminal end of the peptide with the N-terminal /3-strand. Two plant defensins, PhDl and PhD2, feature a fifth disulfide bond and have been proposed to be the prototypes of a new subclass within plant defensins." As a result of these structural features the global structure of plant defensins is notably different from o //3-thionins, which is one of the reasons for the different nomenclature. The structures of plant defensins Rs-AFP ° and NaDf are shown in Figure 6, where they are compared to the thionin /3-purothionin and the structurally more related drosomycin and charybdotoxin. ... 

Figures Comparison of the plant defensin structures Rs-AFP((a), gray, 1ayj)and NaDI ((b), green, 1mr4) with/3-purothionin ((c), magenta, 1 bhp) reveals the structural differences between plant defensins and a//3-thionins. The architecture resembles that of insect defensins, for example, drosomycin ((d), pink, 1 myn) or the scorpion toxin charybdotoxin ((e), yellow, 2crd). The structural similarities become clear in the overlay of Rs-AFP, NaDI, and drosomycin ((f), colors as before).

As exemplarily shown in the case of charybdotoxin, a 37-residue peptide with three intramolecular disulfide bonds,[70] operating in redox buffer was crucial for efficient formation of the correct disulfide bonds.[71] When the reduced peptide was oxidized in 0.1 M NHtOAc buffer (pH 8.0) at 0.11 mM concentration in the presence of redox reagents (peptide/GSH/GSSG ratio of 1 60 6), the main product was the native peptide contaminated... 

The i.c.v. injection of apamin or charybdotoxin, specific blockers of the SK and BK type of Ca2+-activated K+ channels, respectively, prevented the antinociception mediated by tricyclic antidepressants and H1 histamine receptor antagonists whereas 0C2 adrenoceptor-mediated supraspinal analgesia did not depend on the activation of these K+ channels (Table 1). 

Bychkov, R., Burnham, M. P., Richards, G. R., Edwards, G., Weston, A. H., Feletou, M., and Vanhoutte, P. M. 2002. Characterization of a charybdotoxin-sensitive intermediate conductance Ca2+-activated K+ channel in porcine coronary endothelium relevance to EDHF. Br. J. Pharmacol. 137 1346-1354. 

Gao, Y. D., and Garcia, M. L. 2003. Interaction of agitoxin2, charybdotoxin, and iberiotoxin with potassium channels selectivity between voltage-gated and Maxi-K channels. Proteins 52 146-154. 

Miller, C., Moczydlowski, E., Latorre, R., and Phillips, M. 1985. Charybdotoxin, a protein inhibitor of single Ca2+-activated K+ channels from mammalian skeletal muscle. Nature 313 316-318. 

The spinal antinociceptive effect of DPDPE is blocked totally by a small conductance Ca2 + -activated K + channel blocker apamin [109]. The DPDPE-induced spinal antinociception is not inhibited by a ATP-sensitive K + channel blocker glyburide [109], Like morphine, tetraethylammonium, 4-aminopyridine, and charybdotoxin are unable to block the effects of DPDPE [109], These findings suggest that the modulation of apamin-sensitive K + channels appears to play a role in the DPDPE-induced antinociception in the spinal cord. 

In Equation 4.4, ymm is the minimum y value of the curve, ymax is the maximum y value of the curve, cone, is the test concentration, and n is the Hill slope of the curve. We found that the Kv. 3 current was sensitive to inhibition by the Stichodactyla helianthus peptide, ShK, as well as ShK-Dap22, charybdotoxin (all pre-dissolved in water, with 0.1% BSA present during the experiment), and 4-aminopyridine (4-AP), which was dissolved directly in D-PBS (Figure 4.6A). 

A) Concentration-response curves for inhibition of K+ currents by 4-AP (A) and ShK-Dap22 ( ), ShK ( ), charybdotoxin (O), and dendrotoxin ( , data not fitted with curve) peptides. The estimated IC50 values are listed in Table 4.1. Dendrotoxin is a selective Kvll blocker and did not inhibit the Kv 1.3 current in our assay. 

Voltage-gated potassium channels also have a number of different binding sites. Similar to sodium channels, there is a binding site for peptide toxins at the outer vestibule of the pore. This binding site has been identified by site-directed mutagenesis for different peptide toxins, e.g., for the toxin ShK from a sea anemone, which blocks Kvl.3, or for Charybdotoxin, which blocks various potassium channels [19, 20],... 

Archer SL, Huang JM, Hampl V, Nelson DP, Shultz PJ and Weir EK, Nitric oxide and cGMP cause vasorelaxation by activation of a charybdotoxin-sensitive K channel by cGMP-dependent protein kinase. Proc Natl Acad Sci USA 91(16) 7583-7, 1994. 

MacKinnon R, Reinhart PH, White MN (1988) Charybdotoxin block of Shaker K+ channels suggests that different types of K+channels share common features. Neuron 1 997-1001... 

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