Optical Rotatory Dispersion and Circular Dichroism of Neurotoxins Isolated from the Venom of Bungarus multicinctus

Abstract

The optical rotatory dispersion (ORD)^* and circular dichroism (CD)^* of the neurotoxins (α- and β-Bungarotoxin) isolated from the venom of Bungarus multicinctus were measured over the wavelength range of 195 to 300 mμ. The ORD curve of α-Bungarotoxin had a positive peak at 207 mμ and a negative trough at 220 mμ. The CD spectrum of this protein showed a negative maximum at 216 mμ, a positive maximum at 232 mμ and a shoulder at around 240 mμ. Thus, it is suggested that α-Bungarotoxin molecule contains β-structure. On the other hand, the ORD curve of β-Bungarotoxin had a positive maximum at 198 mμ and a negative trough at 232 mμ The CD spectrum had a negative maximum at 210 mμ and a shoulder at 222 mμ Therefore, β-Bungaro-toxin molecule contains α-helical structure. The effects of pH and 2-chloroethanol on the ORD and CD curves of these toxins were also studied.