Protein Crystal Growth, X-ray diffraction and Structure Determination

Proteins are crystallized to provide x-ray data for molecular structural determination. This information is valuable to the pbarmaceutical industry to support drug research.

In addition to growing crystals using the classical vapour vapour diffusion hanging drop technique, Amistar is researching the use of an in-house designed apparatus involving controlled thermal gradients as the crystallization driving force. We have HPLC for protein purification and characterization. Materials currently being grown include cytochrome c, hemoglobin, thaumatin and several lectins. Amistar is attempting to apply its expertise in inorganic crystal grown to protein crystallization.

(Above) 1. Thaumatin I, Mag. 12x.

A sweet protein ( times sweeter than sucrose on a molar scale). M = 22 kDa (207 amino acids). Isolated from the fruits of a West African shrub.

Structure determined to 1.65 Å resolution.

Space group P 212121, orthorhombic a = 74.42 Å, b = 53.38 Å, c = 52.25; 50% of crystal volume is solvent; isoelectric point = 12: 8 intramolecular disulphide bridges.

Ref. Ogata et al., J. Mol Biol. 228, 893-908 (1992).