Use
These are toxic lectins (proteins) from seeds of Abras precatorius. The yellow-white powder is purified by successive chromatography on DEAE-Sephadex A-50, carboxymethylcellulose, and DEAE-cellulose. Abrin A is more positively charged on the DEAE-cellulose column and has been crystallised from (NH4)2SO4 by the free interface diffusion technique. Its molecular weight (by sedimentation equilibrium) is 60,000, whereas Abrin C has molecular weight of 63,800. Treatment of A with mercaptoethanol at 100o/2hours followed by SDSPAGE gave a main band with Mr 32,000 and two very weak bands, whereas C (which is more toxic) gave two intense bands with Mr 28,000 and 33,000. [Wei et al. J Biol Chem 249 3061 1974.] Abrin C has been crystallised for X-ray analysis by the free interface diffusion technique described by Salemme [Arch Biochim Biophys 151 533 1972]. The crystals were grown at 37o in Pyrex tubes (5 x 30 cm) by layering 50l of protein solution (22mg/mL) over 100l of unbuffered 70% saturated (NH4)2SO4 [Wei & Einstein J Biol Chem 249 2985 1974.] [UV and CD: Herrmann & Behnke Biochem Biophys Acta 621 43 1980, for physical and chemical properties see Biochem Biophys Acta 667 397 1981, Beilstein 22 III/IV 6776.]