The Membrane Crystallization Of Protein Solution

The coupling process of membrane distillation and crystallization(membrane crystallization), as a new separation technique,appeared in response to evoiving need. The basic theory of membrane crystallization is removing water from solution through membrane distillation and concentrate solution. Crystals are obtained through induction function of film surface. Compared to other crystallization methods, membrane crystallization has the advantages of controllable process of crystallization, reduced induction time, lower initial concentration of protein and reduced difficulty of nucleation. Suit to X-ray diffraction , high quality macromolecule crystals can be obtained through membrane crystallization technique. We can understand biological active of protein and design new medicine with special targert. It's very important to protein and enzyme science. In this work, crystal conditions of lysozyme and albumin egg were studied using membrane crystallization technique. The main work as follow:1. At the process of membrane crystallization of lysozyme solution, on the basis of investigating kinds of precipitor on the influence of membrane crystallization on crystal shape using static membrane crystallizaiton, the influence of precipitor concentration, stripping solution concentration, protein concentration, pH, temperature, velocity of stripping solution, additives on crystal shape and membrane flux were investigated using continuous membrane crystallization method; Finally, crystal conditions were optimized. The results suggest that protein solution at 20³0mg/mL, precipitor NaCl concentration at 4%～9%,stripping solution MgCl₂ concentration at 16%～25%, pH at 4.7～8.2, temperature at 15℃, velocity of stripping solution MgCl₂ at 0.521mL/min, high quality lysozyme crystals can be obtained. NaCl as precipitor and PEG compounds or tartrate salt as additives can improve the quality of crystals.2. At the process of membrane crystallization of albumin egg solution, the influences of solvent, pH, kinds and concentration of precipitor, stripping solution concentration on albumin egg shape and membrane flux were investigated. The results show that pH 7.3 PBS as solvent, 3%～5%NaCl, (NH₄)₂SO₄ or 3%～7% PEG6000,PEG4000 as precipitor, 15%～25% MgCl₂ as stripping solution, temperature at 15℃, crystals of better shape can be obtained.Membrane crystallization method, as a new method, is differ from other crystal methods. High quality macromolecule crystals can be obtained using this method.