Abstract: AIM: To separate and purify a new anti-clotting protein component(ACPF-7221)from the venom of Agkistrodon.The acute toxicity experiment of ACPF-7221 and the death rate were studied and the LD50 and 95 % confidence interval were determined in mice. METHODS: The venom of Agkistrodon was separated and purified using ion-exchange chromatography of DEAE-Sepharose Fast Flow, molecular sieve filtration through Sephadex G75, SP-Sepharose Fast Flow and molecular sieve filtration through Sephadex G50, the anticoagulation components were recalled using activated partial thromboplastin time (APTT)activity assay.ACPF-7221 was given to mice by intravenous injection, and the dosage was determined according to the body weight of mice.The LD50 and 95 % confidence were calculated by the death outcome. RESULTS: ACPF-7221 was separated and purified, which was a trimer consisted of three kinds of protein and their relative molecular mass were 25000, 30000 and 50000, and the protein level was 65 %.The LD50 of ACPF-7221 was 7.848mg kg, and its 95 % confident interval was 7.353-8.375 mg kg. CONCLUSION: A new anti-clotting protein component ACPF-7221 was extracted from the venom of Agkistrodon by ion-exchange chromatography, which is a trimer consisted of three kinds of protein.The critical orga of acute toxicity is lung, empsyxis asphyxia deduces death.

Key words: snake venom, anticoagulation, acute toxicity, LD50