Crystallization is a common chemical process, many industrial products such as inorganic fertilizer, soda ash, chemical reagents, rubber, rubber, polymers and plastics, vitamins, construction materials, explosives manufacturing, and the crystallization process is a very close relationship. As typical chemical process unit operations, crystal has the following advantages:
① energy consumption. Most compounds is an exothermic crystallization process, and distillation, drying, energy consumption compared to large unit operations, distillation crystalline phase transition potential is only 1/3 to 1/7, only energy intensive separation RUN 10 ~ 30%.
② apply to azeotrope separation of complex systems and so on. Since nearly 90% of the organic compounds for the eutectic-type system, using ordinary distillation methods can not achieve their goals. Use of extraction, azeotropic distillation although other methods can be separated in theory, but the operation by the extraction solvent selection, the actual conditions in the difficult objective to achieve complete separation; Moreover, the extraction agents of other components of the introduction of extended process line, to increase investment and operating costs, and inevitably affect the quality of the final product. And distillation, extraction compared to the crystallization process does not introduce other substances, the high selectivity of the crystallization operation, can be prepared from high purity or ultra-pure products (≥ 99. 9% pure products chromatography).
③ Crystal operating temperature lower, the small degree of corrosion of equipment.
④ improve the operating environment, reduce environmental pollution. Solution crystallization process by changing the operating conditions or the addition of seed material to make the system critical components of solubility (or super saturation) changes, the system changes from the steady-state non-equilibrium steady state, so that a new phase generated to achieve the crystalline material and system, other mixtures separation.
With the development of biotechnology, protein drugs continue to emerge such as biological macromolecules, their unique features more and more attention. As we all know, depends primarily on molecular features of its unique three-dimensional structure. Therefore, to understand the function of determining that a biological macromolecules, we must examine and determine its three-dimensional structure.
On the other hand, understanding the structure of biological macromolecules for drug design, molecular structure and to change or modification of a specific application features are of great importance. X-ray diffraction to determine molecular three-dimensional crystal structure of the most reliable method, but so far for X-ray diffraction of protein crystals of biological macromolecules in this area was still one of the main technical bottlenecks, severely restricting the protein engineering, rational drug Design, synthesis and design of new vaccine development of biotechnology. Protein crystallization is a complex physical and chemical processes, than the crystallization of small molecule compounds, much more difficult, mainly because of its molecular weight and molecular conformation of complex, static characteristics, physical and chemical properties of the instability itself with cofactor, ligand, and other special factors, many of the protein crystallization process is easy to lose in the activity of protein crystal growth so that the work difficult.
Often get the following results: amorphous precipitation, a large number of ceramics, twinning, multiple crystal fusion of body, or defective single crystals. Therefore, in general terms, the current biological macromolecules such as protein crystal growth is still groping and empirical, to some extent also on the opportunity.
Crystal growth has become the obstacle to the advancement speed of the crystal structure analysis of the key issues.
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