Biochemical Homology Between Crystal and Spore Protein of Bacillus thuringiensis

Abstract

The crystalline inclusion of B. thuringiensis, dissolved in 8 M urea containing 10% 2-mercaptoethanol and dialyzed to pH 8. 3 to 8. 5, was compared with a fraction obtained by the same extraction procedure from spores broken by dry rupture. The 2 fractions behaved similarly on chromatography with Sephadex G-100 and DEAE-cellulose. The preparations behaved identically on acrylamide gel electrophoresis at pH 12 and pH 9. 5. Further, peptide maps of the 2 fractions obtained after digestion with trypsin were almost super-imposable. Amino acid analyses of the crystal and spore fraction were closely similar; discrepancies are attributed to contamination of the spore extract with small amounts of other proteins. It is concluded that a significant portion of the spore protein is identical with the crystal protein.