J. Biochem, 2003, Vol. 134, No. 6 799-804
© 2003 Japanese Biochemical Society
BIOTECHNOLOGY |
Isolation, Toxicity and Amino Terminal Sequences of Three Major Neurotoxins in the Venom of Malayan Krait (Bungarus candidus) from Thailand
1 Queen Saovabha Memorial Institute, The Thai Red Cross Society, 1871 Rama IV Rd., Bangkok 10330, Thailand; 2 The Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501; and 3 Zentrum der Rechtsmedizin, Klinikum der Johan Wolfgang Goethe-Universität, Kennedyallee 104, 60596 Frankfurt, Germany
We isolated the most lethal toxins in the venom of the Malayan krait (Bungarus candidus), one of the medically most important snake species in southeast Asia. Three ß-BTx like basic neurotoxins, T1-1, T1-2, and T2, with PLA2 activity were isolated from pooled venom of eight B. candidus from southern Thailand by cation-exchange chromatography, followed by adsorption chromatography on hydroxylapatite and RP-HPLC, with 14-, 16-, and 4-fold increases in toxicity compared to crude venom. The LDs50 determined in mice weighing 18–20 g were 0.26, 0.22, and 0.84 µg per mouse with i.v. injection. T1-1 and T1-2 possessed comparable lethal toxicities to those of ß1-BTx, the most toxic neurotoxin in B. multicinctus venom, and the major neurotoxin in B. flaviceps venom. The apparent molecular weights of the native toxins were approximately 25–25.5 kDa. They consist of two polypeptide chains with apparent molecular weights of 15.5–16.5 and 8–8.5 kDa, respectively. The amino terminal sequences of the two chains of each of the toxins determined by Edman degradation exhibited considerable similarity with those of the A-chains and B-chains of ß-BTxs in the venom of Bungarus multicinctus.
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