BPTI in space group P 212121



This is a real life example for the cell packing in the most common space group for proteins, #19. The model is from our entry 1bpi.pdb, a high resolution structure of Bovine Pancreatic Trypsin Inhibitor. The protein has been used a lot in folding studies.

Space group symmmetry

Here is the molecule alone to the right, and the cell and the original copy of the molecule in it. You can clearly see that the part extending out of the cell has sufficient space to stick into the empty space in the next cell. The pictures have been created with Insight II from Molecular Simulations, Inc (MSI)

From the space group decoding program or from the Tables we find the four symmetry operators and apply them to the asymmetric unit.

(X, Y, Z), (1/2 +X,1/2 -Y, -Z), (-X,1/2 +Y,1/2 -Z), (1/2 -X, -Y,1/2 +Z) 

Finally, here is the complete cell. Try to locate the three 21 screw axes.

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Last revised Dezember 27, 2009 01:40