Crotalocytin : Recognition and Purification of a Timber Rattlesnake Platelet

After being envenomated by the timber rattlesnake. a patient was found to have a platelet count of 5000 per tl. prothrombin time and activated partial thromboplastin time both greater than 1 50 sec. plasma fibrinogen 0 mg/dl. and fibrinogen split products 2560 sg/ml. However. this patient did not appear to have acute disseminated intravascular coagulation since coagulation factors II-XIl were normal. We postulated that this venom contained. in addition to a fibrinogen clotting enzyme, a platelet activating protein. Crotalocytin. Crotalocytin was purified from crude timber rattlesnake venom by Sephadex G-100 gel-filtration, low ionic strength precipitation. and DEAE-A50 Sephadex chromatography. By sodium dodecyl sulfate gel electrophoresis and gel-filtration Crotalocytin was a single chain polypeptide. molecular weight 55.000. Thrombocytopenia after timber rattlesnake bite appeared to be due to a protein that directly activated platelets. Timber rattlesnake bite mimicked the clinical presentation of disseminated intravascular coagulation.