Characterization of two paralysing protein toxins (A-MTX and B-MTX), isolated from a homogenate of the wasp Microbracon hebetor (Say).

Two paralysing toxins (A-MTX and B-MTX) from extracts of Microbracon hebetor (Say) wasps were isolated and purified by gel chromatography, ion exchange chromatography and gel electrophoresis. Both toxins are labile proteins with molecular weights of 43,700 and 56,700, respectively, as estimated by gel chromatography, and with isoelectric pH of 6.85 and 6.62, respectively. Both toxins are inactivated by proteolytic enzymes and by dithiothreitol, but A-MTX appears to be more resistant than B-MTX. The relative amino acid compositions of both toxins show great similarity. The biological effects of the two toxins were identical to those previously found for crude toxin preparations.