Lysozyme Crystal Growth Under Forced Solution Flow Condition

Proteins play a key role in all biological process. Recently, nuclear magnetic resonance studies of protein solutions have yielded atomic structure information for some small proteins. However, for proteins with molecular weight in excess of 20000, only X-ray and neutron diffraction techniques can provide structure information to atomic resolution, such studies require single crystals of high structural perfection.The most important factors for growing high-quality protein crystals is the purity of the protein solution and solution covection effects. So it is very important to study the effects of impurity and solution covection effects on protein crystallization.In this thesis, lysozyme was selected as model protein. Compared to commercial lysozyme and high-purity lysozyme, the influence of fluorescence-labeled lysozyme (F-lysozyme) on morphology, quality of lysozyme crystal under different growth conditions were studied with high-resolution phase contrast microscopy. The protein crystal growth on a rotary plate is also researched. The absorption of impurity on the crystal can be obtained with etch method.Etch pit density of commercial lysozyme crystals was approximately ten times greater than that of pure crystals (F-lysozyme included). Flat etch pit density increased with concentration of F-lysozyme by exponential growth function relation. Flat etch pit density also decreased with normal growth rate of {110} face, which could be explained by equilibrium adsorption model and Burton-Prim-Slichter model. The curve of the number of flat etch pit density on {110} face changed with time under certain concentration of F-lysozyme, indicated that the incorporation of impurity on {110} crystal face slowly decreased in the process of lysozyme crystallization.The flat etch pit density of commercial lysozyme crystals changes with angular velocity by parabola function relation. The flat etch pit density of commericial lysozyme crystals reduces when angular velocity increases. The flat etch pit density of commercial lysozyme crystals is minimus under a specifical angular velocity. The flat etch pit density of commercial lysozyme crystals will increases if the angular velocity which is more than the specifical velocity increases. The rotary flow field affect protein crystal growth process. The rotary flow field reduce the absorption of impurity and protein solute on protein crystal surface. The flat etch pit density of commercial lysozyme crystals is minimus under a specifical angular velocity. The rotary flow field also affect deep etch pit density of commercial lysozyme crystals. Rotary flow field affect protein crystal growth dynamics because the deep etch pit density is related to protein crystal growth dynamics.