Characterization and some properties of the venom gland extract of a theridiid spider (Steatoda paykulliana) frequently mistaken for black widow spider (Latrodectus tredecimguttatus).

The simplified purification protocol established for the isolation of alpha-latrotoxin from the venom of the spider Latrodectus tredecimguttatus, has been employed for the purification of toxic components present in the venom of the spider Steatoda paykulliana. The venom of this spider, frequently mistaken for L. tredecimguttatus, is by tradition considered to cause an envenomation potentially dangerous to man. The venom of S. paykulliana has little toxic effect on guinea-pigs but is extremely toxic to houseflies (Musca domestica). No proteolytic activity was detectable. Interaction of microgram/ml amounts of the venom extract with artificial lipid membranes produces an increase of membrane conductance through the formation of stable ion-permeable channels modulated by the direction and size of the electric potential differences across the membrane. Higher concentrations of this venom are able to stimulate the release of transmitters from neurosecretory cells in a fashion reminiscent of black widow spider venom. Antibodies against the whole L. tredecimguttatus venom gave a few positive cross-reactions in the immunodiffusion test with S. paykulliana venom gland extract indicating the presence of common molecular sequences in the two venoms. Polyclonal antibodies against alpha-latrotoxin did not cross-react in the immunodiffusion test with S. paykulliana venom extracts, nor in the immunofluorescence assay with its cephalothorax sections, thus suggesting that the venom glands do not contain alpha-latrotoxin. A partial characterization of S. paykulliana venom has been performed and a high molecular weight protein toxic to houseflies has been partially purified.