The venoms of many kinds of spiders such as black widow spider (Latrodectus tredecimguttatus) are known to contain a multitude of components toxic to animals and insects.However,it may not be widely known that black widow spiders have toxic components not only in their poisonous glands,but also throughout their body,including the legs and abdomen,and even in the eggs and the newbom spiders.The present study isolated a proteinous toxin from the black widow spider eggs using a combination of gel filtration,ion exchange chromatography and reversed-phase chromatography.Electrospray mass spectrometric analysis indicated that the molecular weight of the protein is 28.69 kDa,and the N-terminal sequence of the protein was determined by Edman degradation to be ESIQT STYVP NTPNQ KFDYE VGKDY-.By employing multiple proteomic strategies,the isolated protein was demonstrated to have only a few similarities to the existing proteins in the databases,suggesting that it is novel protein isolated from the eggs of black widow spiders.After being abdominally injected into mice and P.americana,the protein could make the animals especially P.americana become depressed and move slowly.Preliminary electrophysiological experiments demonstrated that the protein can inhibit voltage-activated Na+ channels currents in rat dorsal root ganglion neurons,exhibiting important potentials in the research of neurophysiology and the development of pharmaceuticals and insecticides.