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Abstract:
The parasporal inclusions of Bacillus thuringiensis are small protein crystals. Chemical composition, density of the particles and sedimentation behaviour of the dissolved protein are briefly reported. X-Ray diffraction of powder preparations gives a rich spectrum of closely-spaced lines extending from spacings of 100 Å to 20 Å and beyond. Analysis of these results reveals a tetragonal unit cell in which a = 90 Å and c = 269 Å. The results are consistent with a space group of P41212. They correlate well with the fine structure as seen by electron microscopy if the strongly developed faces seen in electron micrographs are assumed to be the (101) faces of the tetragonal unit cell. The molecular packing is discussed, and a molecular weight of about 230,000 is deduced for the asymmetric unit.
