[Proteins of Bacillus thuringiensis delta-endotoxin crystals]

Pure crystals (at least 99% purification) of sigma-endotoxin were isolated from Bac. thuringiensis var. galleriae. The complete dissolution of crystals might be achieved by the increase of pH up to 12 and higher or by a combined action of S = S-reducing and denaturing agents. Electrophoresis of the solubilized crystal proteins in 5% polyacrylamide gels containing 0,1% sodium dodecyl sulfate and 8 M urea reveals two major bands corresponding to molecular weights of 120000--140000 (65%) and 65000 (8-10%), and some minor components whose molecular weights varied from 65000 to 340000. Urea (3--8 M) causes to partial dissolution of the crystals; the component with molecular weight of 65000 is mainly found in the solution (component A). In dithioerythritol extracts at pH 9 the major component of the crystal is the protein with molecular weight 120000--140000 (component B). The crystals, alkali-soluble components and proteins isolated from crystals by selective extraction (3--8 M urea or 0.01 M dithioerythrytol, pH 9) were found toxic for the larvae of Galleria mellonella.