Dean D. Watt

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1. The effect of various toxin fractions isolated by Watt et al. (1978) from the venom of the scorpionCentruroides sculpturatus Ewing on the Na currents of the node of Ranvier has been studied with the voltage clamp method. 2. The toxin fractions were applied externally. The most potent fractions were toxins III, IV and V which were effective in(More)
(1) Gating currents were recorded from frog nodes of Ranvier treated either with toxins III or IV from the venom of the scorpionCentruroides sculpturatus or with the alkaloid toxin aconitine. (2) Toxins III or IV fromCentruroides sculpturatus (which drastically reduce the sodium permeabilityP Na and slightly shift its voltage dependence in the depolarizing(More)
We report the detailed solution structure of the 7.2 kDa protein CsE-I, a beta-neurotoxin from the New World scorpion Centruroides sculpturatus Ewing. This toxin binds to sodium channels, but unlike the alpha-neurotoxins, shifts the voltage of activation toward more negative potentials causing the membrane to fire spontaneously. Sequence-specific proton NMR(More)
1. The specific binding to rat brain synaptosomes of a radiolabelled derivative of toxin II from the scorpionCentruroides suffusus suffusus could be prevented by toxins III and IV, but not by toxin V or variants 1–3, from the venom ofCentruroides sculpturatus. 2. The specific binding of a similar derivative of toxin II fromAndroctonus australis Hector was(More)
The further characterization of toxin I from venom of the scorpion Centruroides sculpturatus Ewing (region, Southwestern United States) is reported. Toxin I is a single palypeptide chain of 64 amino acid residues crosslinked by four disulfide bridges. The complete amino acid sequence of toxin I was deduced from the sequence of its tryptic peptides and(More)
1. In nodes of Ranvier treated with toxin III or IV from the scorptionCentruroides sculpturatus Ewing a strong positive pulse is followed by a transient shift of the descending branch of theI Na(E) curve to more negative values of membrane potential (cf. Meves et al. 1982). This effect was studied in more detail, using toxin concentrations between 0.8 and(More)
It is evident from the data reviewed that scorpion toxins can be distinguished on the basis of three properties: their effects on Na currents, their specific binding to excitable membranes, and the effects of depolarization and pH on binding and on effect. Additional work with other scorpion toxins is required to establish the degree of correlation between(More)
1. An oscillation in resting tension of the chick biventer cervicis muscle is induced by scorpion toxin (CsT-V), reduced [Ca]o and by Cd2+. Other chick muscles, e.g. semispinalis cervicis, anterior and posterior latissimus dorsi, also oscillate with the same treatments. The period of the oscillation in the biventer cervicis muscle is uniform, averaging 5-6(More)
We report a preliminary high-resolution proton nuclear magnetic resonance characterization of the variant-3 toxin from the scorpion Centruroides sculpturatus Ewing (range Southwestern USA). This toxin assumes a well defined folded conformation in aqueous solutions at room temperature and undergoes reversible thermal denaturation. A number of amide hydrogens(More)