The IOBCr community is interested in growing crystals with biomolecules because they provide a means to study the architecture of the molecules making up the crystals. A crystal is composed of (bio)molecules assembled in a regular, 'periodic' way in the three dimensions.
This regularity or periodicity is at the origine of the diffraction phenomenon when a crystal interacts with X-rays. The resulting signal is used by crystallographers to determine 3D pictures of the molecules that constitute the crystal.
From the biomolecule to its 3D picture