Case history: Shiga-like toxin B-subunit + trisaccharide

• Crystals diffract to 2.8Å, very weak beyond 3.5Å

• Four pentamers in asymmetric unit

  • two related by translational NCS (native Patterson)

• Solved by molecular replacement

• Rigid-body refinement of 20 monomers

  • 5-folds not exact

• 20-fold averaging with 20 envelopes

  • plus one-fold envelope for binding sites

• Trisaccharide density became very clear

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Last updated: 7 June, 2005