Crystal-packing interactions

The crystal structures of lipases described to date are static descriptions of conformational states, possibly stabilized in some cases by crystal packing interactions. What is lacking is the dynamic component What initiates the conformational transition Is there a true lipid-recognition site that triggers the change, and does a simple two-state model come sufficiently close to the actual phenomenon Or, does the interface simply stabilize one of the conformations existing in solution in an equilibrium And just how stable is the inactive conformation ... 

Conformational polymorphs conformational polymorphs are different pure crystal forms of the same snbstance that differ in one or mode bond rotations in the molecular structure. The implication is that these two or more conformers are in rapid equilibrinm under the conditions under which the crystal formed and hence usnally represent rotations about single bonds. If this were not the case the different conformers wonld be distinct isomers and would be formally different chemical substances and hence not polymorphs. Crystal packing interactions can stabilise particular conformers that are relatively unstable in solntion and hence crystals can contain sometimes surprising conformational isomers. A remarkable example is trans-l,4-diethynylcyclohexane-l,4-diol which has two forms (A and... 

Disrupting crystal packing interactions Making appropriate salts Using a prodrug approach... 

Chemical structure data must unambiguously define the atomic connectivity within the molecule, and in many cases, the precise 3D coordinates of all atoms. Additional data is often present, although its nature is highly dependent upon the subdomain that the data represents - structures determined analytically by X-ray diffraction will include crystal-packing interactions structures computed with quantum chemical methods may include partial electronic charges structures associated with a corporate synthetic program may lack 3D coordinates, but may include such mundane information as inventory and sample location. 

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