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高分子对酶促反应的促进作用（1）在葡萄糖脱氢酶（GDH）中加入阳离子高分子如聚乙烯亚胺（PEI）和DEAE-葡聚糖，可显著提高GDH的热稳定性。据推断，吸附的聚合物的GDH阻止解折叠的GDH通过多点结合。(2)在低辅酶（NAD（）^+）浓度下加入PEI可提高GDH催化反应的速率。动力学研究结果表明，PEI介导的辅酶NAD（P）^+在GDH附近的富集与PEI相互作用导致了这种加速效应。(3)在乳酸脱氢酶（LDH）/GDH偶联体系还原苯丙氨酸（PhP）的反应中，PEI的加入对提高反应速率有明显作用。(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PhP的转化率.水溶性高分子对酶膜反应器性能的影响在连续式中空纤维酶反应器中LDH/GDH偶联酶体系对PhP的连续还原反应中，PEI的加入对提高PhP的转化率是有效的.等离子体接枝聚合法制备膜酶反应器用微孔荷电膜通过在聚乙烯微孔膜上接枝丙烯酸制备微孔荷电膜，并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.