Stabilization and Activation of Enzymes by Adsorptive Immobilization with Water-Soluble Polymers and Its Application to Enzyme Membrane Reactor

1.酶的稳定性及水溶性聚合物对酶反应的促进作用(1)通过加入水溶性阳离子聚合物聚乙烯亚胺(PEI)和DEAE-葡聚糖，显著提高了葡萄糖脱氢酶(GDH)的热稳定性。结果表明，聚合物在GdH上的吸附通过多点结合阻止了GdH的去折叠。(2)低浓度的辅酶(NAD+)加入PEI可以提高GdH的催化反应速度。动力学研究结果表明，PEI与辅酶NAD(P)~+的相互作用对酶促反应有促进作用。(3)在乳酸脱氢酶(LDH)/GDH偶联体系还原苯丙酮酸(PHP)中，加入PEI对提高反应速度非常有效。(4)PEI的加入提高了乙醇脱氢酶(ADH)催化反应的表观平衡常数，从而提高了LDH/ADH催化反应中苯丙酮酸的转化率。水溶性聚合物对膜反应器性能的影响在LDH/GDH共轭酶体系连续还原苯酚的中空纤维型连续酶反应器中，投加PEI能有效地提高PhP.3的转化率。采用等离子体接枝聚合法制备膜酶反应器用的微孔荷电膜，将丙烯酸接枝到微孔聚乙烯膜上制备微孔荷电膜，研究了制备条件对膜性能的影响。成功地制备了具有高电荷密度的膜。

1. Stabilization of enzymes and accelerating effect of water-soluble polymers on enzymic reaction(1) By addition of water-soluble cationic polymers such as polyethyleneimine(PEI) and DEAE-dextran, thermal stability of glucose dehydrogenase (GDH) was remarkably increased. It was deduced that adsorption of polymers to GDH prevents unfolding of GDH by multi-point binding.(2) The rate of GDH-catalyzed reaction was enhanced by addition of PEI at low coenzyme(NAD()^+) concentration. The results of kinetic study suggested that the accelerating effect is due to PEI-mediated enrichment of coenzyme NAD(P)^+ near GDH interacting with PEI.(3) In the reduction of phenylpyruvic acid(PhP) by lactate degydrogenase(LDH)/GDH conjugate system, addition of PEI was very effective for increasing reaction rate.(4) The apparent equilibrium constant of alcohol dehydrogenase(ADH)-catalyzed reaction was increased by addition of PEI, resulting in improvement of the conversion of PhP in LDH/ADH-catalyzed reaction.2. Effect of water-soluble polymers on performance of enzyme membrane reactorIn the continuous reduction of PhP by the LDH/GDH conjugate enzyme system using a continuoustype hollow fiber enzyme reactor, addition of PEI was effective for increasing the conversion of PhP.3. Preparation of microporous charged membrane by plasma-graft polymerization for membrane enzyme reactor.Microporpus charged membranes were prepared by grafting acrylic acid to microporous polyethylene membranes, and the effect of preparation condition of the membrane properties was studied. Membranes with high charge density were successfully prepared.