The snake venom and bacterial toxins are exploitive proteins. These come under the category of

They are protective proteins which protect the body from ill effects of poisonous (toxic) substances and pathogenic invaders (virus, bacteria and other pathogens) by destroying the toxins and invaders. Important defense proteins are antibodies or immuno-globulins produced by lymphocytes in vertebrates. Interferon protects cells from the attack of viruses. Thrombin and fibrinogen form blood clots to prevent loss of blood and infection at the sites of the injuries. Certain proteins, called exploitive proteins, are normally toxic, but these may play a defensive role under certain conditions. These include snake venom, bacterial toxins and toxic plant protein called ricin.