多酶催化与辅酶再生耦合体系仿生构建的研究

Conversing carbon dioxide to resources showed great significance on the area of science as well as technology. However, there is less of green strategy for conversing CO2 efficiently and continuesly. In this research, (1) CO2 was catalytic conversed to lactic by a immobilized multienzyme system (The multienzyme system constituts of alcohol dehydrogenase, pyruvate decarboxylase, lactate dehydrogenase and carbonic anhydrase), which ensured a green coversion process. ( 2) A novel template was synthesised through grafting reaction which use positively charged polymer as nitrogen source and graphene as carbon source. It induced biomimetic mineralization of titanium dioxide ( TiO2 ). The C-N doped TiO2 nanoparticles acted as enzyme carrier, and then coupled the process of enzyme catalysis and photocatalysis. It ensured that coenzyme nicotinamide adenine dinucleotide ( NADH ) was synergistic regeneratted and CO2 was efficiently conversed; ( 3 ) Through constructing nano-micro multi-scale carrier for enzyme immobilizztion, advanced structure and protection mechanism of cell was simulated. the primary catalytic state reductase, Enzyme activity was retained effectly becasuse the original catalytic condition was repeated. At the same time, based on CO2 concentrating mechanism of diatom cell, the carbonic anhydrase ( CA ) was introduced into the immobilized multienzyme system, which strengthen the substrate mass transfer and ensured continues conversion of CO2. It is important for clarifying the "immobilization method-enzyme microenvironment-catalytic properties" relationship, and the between, elucidating the process-strengthening mechanism, and summing up the principle of rational construction of multienzymatic system.

CO2资源化利用具有重大科学意义和应用价值，其难点在于设计合理路径实现绿色、高效、持续转化。本研究提出利用固定化多酶体系（包含醇脱氢酶、丙酮酸脱羧酶、乳酸脱氢酶、碳酸酐酶）催化CO2转化为乳酸，实现CO2绿色转化的思路：（1）利用多氨基荷正电高分子为氮源、石墨烯为碳源，将二者接枝后作为诱导剂，引发二氧化钛（TiO2）仿生矿化。以此C-N共掺杂TiO2作为纳米载体固定化酶，使酶催化与光催化协同，促进辅酶烟酰胺腺嘌呤二核苷酸（NADH）还原再生，实现CO2高效转化；（2）构建纳-微多尺度固定化酶载体，模拟细胞高级结构及保护机制，还原酶的原生催化状态，有效维持酶活力和稳定性。（3）基于硅藻细胞的CO2浓缩机制，将碳酸酐酶（CA）引入固定化多酶体系，强化底物传质，实现CO2可持续转化。本研究的成功实施可揭示酶固定化方法-微环境-催化特性之间的关系，建立多酶催化体系理性构建方法，实现催化过程强化

二氧化碳（CO2）资源化利用具有重大科学意义和极高应用价值。本研究拟以多酶催化CO2转化为研究对象，利用仿细胞结构的纳-微多尺度载体固定化“醇脱氢酶-丙酮酸脱羧酶-乳酸脱氢酶”体系，催化CO2转化为乳酸。1）在细胞器结构启发下，制备有机-无机纳米复合载体固定化酶。通过氧化-还原-氨化反应，利用小分子多胺接枝改性长链负电多糖海藻酸，得到双功能高分子氨基化海藻酸。“催化功能”使其具备了诱导仿生矿化的能力，可在前驱体浓度较低的条件下催化生成纳米二氧化硅颗粒固定化酶，“模板功能”则导致其在水溶液中形成胶束，引起微观相分离。改变氨基化海藻酸的制备条件，可以调节胶束粒径，从而控制纳米载体的形态和大小；2）为了模拟细胞质结构，以具有热可逆相变特征的高分子明胶作为材料，设计制备单分散微球固定化酶。通过膜乳化法制得的明胶微球粒径在15-80μm范围内，且粒度均一 、分布较窄，进一步研究表明明胶微球粒径与SPG膜孔径具有线性关系，可实现固定化酶载体的可控制备；3）为模拟硅藻细胞壁结构，将仿生矿化法与膜乳化法结合，设计制备结构新颖的有机-无机杂化微球用于固定化酶。含酶水相明胶溶液与油相液体石蜡混合搅拌后形成预乳液，通过SPG膜后与硅源前驱体（预水解的正硅酸乙酯溶液）混合，在乳液滴界面处原位发生仿生矿化，形成规整、均匀、致密的仿细胞壁结构二氧化硅壳层。纳-微米多尺度固定化酶模拟了活细胞对酶的保护机制，使固定化酶的pH耐受性和储存/循环使用稳定性显著提高。利用新型光催化材料氮化碳，构建多孔结构并固定化酶，实现了光-酶耦合催化辅酶再生。本项目的研究还原了酶的原生催化状态，有效维持酶活力，实现CO2绿色、高效、持续转化。通过探索酶固定化方法-微环境-催化特性之间的关系，实现多酶反应器理性构建和催化过程高效强化。