Protein crystallization was discovered by chance about 150 years ago and was developed in the late 19th century as a powerful purification tool and as a demonstration of chemical purity. Hemoglobin crystals from worms and fishes were the first protein crystals observed by German biologists. Nevertheless, they have remained a laboratory curiosity for many years until Ritthausen crystallized, for the purpose of purification, a series of plant seed proteins. The demand for protein crystals expanded rapidly in the 1960s and 1970s as protein crystallography took off. X-ray crystallographers depended very much on the successes of earlier protein chemists, and on their somewhat limited procedures and technologies, to provide suitable samples for diffraction.
Macromolecular crystallization, which includes the crystallization of proteins, nucleic acids and larger macromolecular assemblies such as viruses and ribosomes, is based on a rather diverse set of principles, experiences and ideas. There is no comprehensive theory to guide our efforts, although several are being accumulated at this time. As a consequence, macromolecular crystal growth is largely empirical in nature, and demands patience, perseverance and smart, efficient tools for research.
The crystallization of proteins, nucleic acids and large biological complexes, such as viruses, depends on the creation of a solution that is supersaturated in the macromolecule but exhibits conditions that do not significantly perturb its natural state. The objective is then to alter matters so that the solubility of the protein in the sample is significantly reduced, thereby rendering the solution supersaturated. This may be performed through several approaches, such as:
Protein crystallization usually requires a significantly great amount of protein and in most of the cases the quantity of material available is severely limiting. The CrystalBreeder instrument is the next generation multi-reactor crystallization platform for medium-throughput solid-state research, operating at a working volume of 0.06 - 0.1 mL. You can now carry out rapid complete crystallization screens with as little as 1 mg of sample. The CrystalBreeder gives you real time turbidity information for 32 parallel temperature controlled experiments. The reaction conditions are more reproducible and realistic than in well-plate experiments. Through the vial analytics measure the turbidity in each reactor without any physical contact with the sample. The real-time display of the results provides an immediate and reliable signal when a sample crystallizes. Multiple crystallization methods are now possible with the CrystalBreeder instrument. Vapor diffusion into liquid and onto solids was never easier. Cooling, evaporation, anti-solvent, slurry, thermocycling, vapor diffusion crystallization are now possible, reproducible and easily accessible.