Purification and characterization of a lethal factor in venom from the crown-of-thorns starfish (Acanthaster planci).

A lethal factor in venom of the crown-of-thorns starfish (Acanthaster planci) was obtained in an electrophoretically pure state by chromatography on CM-cellulose and Sephadex G-100. The purified lethal factor is a basic (pI 10.6) glycoprotein (carbohydrate content 3.5%). The mol. wt was estimated to be 20,000 by gel filtration or 25,000 by SDS-disc electrophoresis, suggesting that the lethal factor has no subunit structure. Despite its basicity, the lethal factor was richer in acidic amino acids than in basic amino acids. The lethal factor had an LD50 of 0.43 mg/kg (i.p. injection into mice). Hemolytic, edema-forming and capillary permeability-increasing activities, though very weak, were also exhibited by the lethal factor, while hemorrhagic and phospholipase A activities were not present.