Abstract

AHMED, M et al. Enzymatic and biochemical characterization of Bungarus sindanus snake venom acetylcholinesterase. J. Venom. Anim. Toxins incl. Trop. Dis [online]. 2012, vol.18, n.2, pp. 236-243. ISSN 1678-9199.  http://dx.doi.org/10.1590/S1678-91992012000200014.

This study analyses venom from the elapid krait snake Bungarus sindanus, which contains a high level of acetylcholinesterase (AChE) activity. The enzyme showed optimum activity at alkaline pH (8.5) and 45ºC. Krait venom AChE was inhibited by substrate. Inhibition was significantly reduced by using a high ionic strength buffer; low ionic strength buffer (10 mM PO₄ pH 7.5) inhibited the enzyme by 1. 5mM AcSCh, while high ionic strength buffer (62 mM PO₄ pH 7.5) inhibited it by 1 mM AcSCh. Venom acetylcholinesterase was also found to be thermally stable at 45ºC; it only lost 5% of its activity after incubation at 45ºC for 40 minutes. The Michaelis-Menten constant (Km) for acetylthiocholine iodide hydrolysis was found to be 0.068 mM. Krait venom acetylcholinesterase was also inhibited by ZnCl₂, CdCl₂, and HgCl₂ in a concentrationdependent manner. Due to the elevated levels of AChE with high catalytic activity and because it is more stable than any other sources, Bungarus sindanus venom is highly valuable for biochemical studies of this enzyme.

Keywords : acetylcholinesterase; inhibition; krait; ionic strength; acetylthiocholine iodide; Bungarus sindanus; snake venom.