Studies On Nonionic Surfactant Coating Of Proteins And Mixed Reversed Micelles

Generally, electrophoresis separation of proteins is carried out in water buffers. Semi-preparative or preparative electrophoresis is urgently needed to enlarge the scale by the development of research and practical demand. However, usual methods of enlarging scale bring about serious Joule heating resulting in many phenomena which makes the separation meaningless. Actually, the Joule heating becomes the bottle-neck of the enlargement of electrophoresis.At the same voltage, the current in organic buffer is obviously lower than the water for the dielectric constant of organic solvent is usually smaller than water. Then it can deduce effectively the Joule heating to reach the aim of enlargement. However, proteins are easy to be inactivated in organic solvents. How to protect proteins from inactivation becomes a new challenge in the electrophoresis in organic solvents.In this paper, two systems to protect proteins from inactivation in the organic solvents were researched: non-ionic surfactant coating of enzymes and mix reversed micelles.Firstly, a series of non-ionic surfactants glutamic acid dialkyl ester ribitol amides were synthesized. Four selected enzymes (two lipases, pepsin and lysosome) as objects were researched by orthogonal test to get the optimized conditions of preparation by evaluation on integrated factors of productivity and activity of coating enzymes. The activities of coating enzymes were studied by esterification of lauric acid and lauryl alcohol as the model reaction. Several factors effecting coating process were discussed: kinds and concentration of ions, pH value, organic solvents, time of ultrasonic operation, kinds of surfactants, usage ratio of surfactant to enzyme and time of cold storage etc. Finally the mechanism of coating and principle of activity were discussed in detail.Secondly, by investigating the conductivity of mixed reversed micelles of ionic surfactants (such as AOT and CTAB) with different kinds of non-ionic surfactants, this paper found matches of AOT/Tween80 and CTAB/Tween85 were favorable. And the molar ratio of ionic surfactants to non-ionic surfactants, salt concentration and the concentration of surfactants were the main factors influencing the structure and character of mixed reversed micellers system. This paper screened out appropriate systems to make the amount of water dissolved and stability of mixed reversed micelles to a better condition synchronously. The activity and stability performance of mixed reversed micelles were investigated by hydrolysis reaction of olive oil as a model reaction. It was found that the adding of non-ionic surfactant increased the activity and stability of enzymes.Finally, the stability of reversed micellers in high temperature was investigated. The experiments clearly showed that percolation transition of CTAB/Tween85 did not happen with increasing temperatures. Its stability performance was good.