A toxin that recognizes muscarinic acetylcholine receptors. Preparation and characterization of crystals suitable for structural analysis.

Muscarinic toxin 2 from Dendroaspis angusticeps has been crystallized by vapour diffusion, in sodium acetate using sodium thiocyanate as a precipitant. Trigonal crystals (space group P3(1)21 or P3(2)21) have been obtained. The unit cell parameters are a = b = 64.2 A and c = 37.1 A. The presence of one molecule per asymmetric unit is estimated.