非水相固定化生物催化的研究进展

非水相固定化生物催化技术有效拓宽了生物催化过程研究的应用范围。本文分别介绍了水-有机溶剂两相以及离子液体、超临界流体、质子惰性有机溶剂和深低共熔溶剂等新型非水相介质以及无机和高分子载体及无载体固定化技术在生物催化研究中的应用进展。展现了各种非水相介质与固定化技术对底物溶解度、酶的稳定性及产物产量等性能的促进作用,体现了其对酶活及生物催化反应的选择性等方面的不利影响,而且突出显示了非水相介质与固定化技术的结合是提高酶和微生物的活性、稳定性与选择性等性能的一个有效手段,再通过生物反应器的选择或设计以及工艺优化,有助于一些生物催化过程更高效地实现工业化。     

水-有机溶剂两相体系中面包酵母不对称还原苯乙酮合成手性苯乙醇的研究

以面包酵母细胞不对称还原苯乙酮合成S-α-苯乙醇为模型反应,研究了水-有机溶剂两相体系促进面包酵母细胞催化芳香酮的不对称还原情况.首先研究了适合于活性细胞催化的两相溶剂体系,实验表明合适的有机溶剂为logp3的溶剂,这与有机相中的酶催化对溶剂的要求相一致.在所选用的溶剂中,正辛烷获得的效果最好.在此基础上进一步考察了两相之间的比率、辅助溶剂、底物浓度以及水相体系的pH等对反应的影响.实验表明两相之间的比率和辅助溶剂对反应有显著的影响,合理改变这些因素可以改善底物在两相之间的分配进而促进反应的进行.反应对底物浓度的敏感性较单相水相体系反应要小得多,而pH对反应的影响与水相中反应相同.在有机溶剂与水相体积比为1:4、添加1%乙醇以及底物浓度为30 mmol·L-1时,产物得率可达到45%左右,这较在水相中反应有显著的提高.     

糖苷类化合物非水相生物催化结构修饰的研究进展

介绍了非水相生物催化的现状,包括常用催化剂种类如游离酶、固定化酶和全细胞催化剂,常见的非水相催化介质如有机溶剂体系、无溶剂体系、离子液体体系以及超临界流体介质体系,阐述了糖苷类化合物的去糖基化修饰、糖基化修饰、酰化修饰以及甲基化修饰等方法,并叙述了结构修饰对化合物性质的影响,如提高化合物的溶解度、增强化合物的稳定性以及提升化合物的生物活性等,简单介绍了目前糖苷类结构修饰化合物的相关应用。     

深度学科交叉和高度过程集成的非水相生物催化

和化学合成相比,生物催化具有选择性高、反应条件温和、环境友好的特性而成为生物技术中一个快速发展的领域.但生物催化工业常受到底物溶解度低、底物/产物抑制生物催化剂活性、产物进一步降解等限制.非水相催化和原位产物去除新技术是克服上述困难的有力工具,本文综述了其研究进展.以甾醇边链切除的微生物转化为例,介绍了作者最近开发的高度集成了非水相催化和原位产物去除优点的浊点两相分配生物反应器技术.讨论了非水相生物催化工业高度过程集成和深度学科交叉的特征,提出了发展非水相生物催化工业的若干建议.     

甲基立枯磷合成方法的研究

本文报道了甲基立枯磷合成的三种方法:1.水溶剂法;2.有机溶剂法;3.相转移催化合成法。通过对溶剂缚酸剂、催化剂的条件试验,筛选出以TEBA为催化剂的优惠方法。试验结果表明:相转移催化合成法收率与日本专利报道相当(略有降低),但反应周期缩短,操作简便,后处理分离容易。     

1,2,3-三氯苯氨解制备2,3-/2,6-二氯苯胺的工艺研究

研究了以1,2,3-三氯苯为原料催化氨解制备2,3-/2,6-二氯苯胺。通过筛选催化剂,溶剂和相转移催化剂,确定Cu2O做催化剂,水做溶剂,PEG-400做相转移催化剂的反应体系。采用正交实验优化了催化剂用量、反应温度、氨水浓度以及NH3与1,2,3-三氯苯摩尔比。在最佳工艺条件下反应40 h,1,2,3-三氯苯转化率为69.3%,2,3-/2,6-二氯苯胺选择性为93.5%。     

Solvent effect on catalytic synthesis of chiral compouds with lipase and penicillin G acylase

生物酶催化合成手性药物和中间体具有高效、节能和环境友好等突出的优势,本文从提高催化反应效率的角度,评述了非水相酶催化反应的溶剂效应——溶剂体系对酶的活性和对映选择性的调控作用;介绍了动力学控制合成β-内酰胺类抗生素的不同溶剂体系,包括有机物-水共溶剂体系、有机物-水不共溶剂体系、反胶束体系和双水相体系。提出利用溶剂效应调控动力学合成体系,会有效提高酶催化合成β-内酰胺类抗生素的产率和合成与水解比S/H值,从而实现底物的有效利用。     

脂肪酶和青霉素酰化酶催化合成手性化合物的研究进展

生物酶催化合成手性药物和中间体具有高效、节能和环境友好等突出的优势，本文从提高催化反应效率的角度，评述了非水相酶催化反应的溶剂效应——溶剂体系对酶的活性和对映选择性的调控作用；介绍了动力学控制合成β-内酰胺类抗生素的不同溶剂体系，包括有机物-水共溶剂体系、有机物-水不共溶剂体系、反胶束体系和双水相体系。提出利用溶剂效应...     

玉米芯提取液还原制备纳米钯催化剂及其催化Suzuki偶联反应的研究

以玉米芯提取液为还原剂,在PVP保护下制备了钯纳米催化剂(Pd NPs)。通过正交实验,筛选了氯钯酸钠、提取液和PVP用量以及还原温度等制备条件对PdNPs催化Suzuki偶联反应的影响,确定了最佳制备条件。考察了最佳条件下制备的Pd NPs催化Suzuki偶联反应中碱、溶剂、溶剂与水比例、反应时间等反应条件对反应的影响。实验结果表明:当反应过程中选取碱为Na_2CO_3、溶剂为EtOH/H_2O(体积比1∶1)、反应温度为40℃、催化剂用量为底物的0.01mmol%时,催化对溴甲苯与苯硼酸的Suzuki偶联反应产物收率达到99.29%。     

木质素氢解反应溶剂与催化剂研究进展

木质素是由三种苯丙烷单元随机键合形成的复杂大分子物质,是自然界中唯一可直接提供芳环的可再生能源。以木质素为原料制取高品位液体燃料和高附加值化学品,特别是木质素氢解是国内外关注的热门研究领域之一。梳理了近年木质素催化氢解研究进展,针对木质素氢解过程中溶剂体系（水溶剂以及醇类溶剂）和催化剂体系（均相催化剂以及非均相金属催化剂）对木质素氢解效率、产物分布的影响机理,做了较全面的概述和分析。最后,针对木质素催化氢解领域目前尚存在的问题提出建议,期望为木质素高值化利用相关研究提供参考。     

极端微生物与工业生物催化剂开发

工业催化领域对生物催化剂提出了苛刻的要求,特别是高浓度底物或产物、高离子强度、酸碱条件及其非水相催化,如何获得高效的生物催化剂是催化技术发展的关键。极端微生物是高效工业生物催化剂的重要来源,本文主要介绍从嗜热菌、嗜盐菌或耐盐菌、耐辐射微生物、耐有机溶剂等极端微生物出发发现并开发高效工业生物催化剂,可望为生物技术的进一步发展提供一个更广阔的资源。     

生物催化及其在手性技术中的应用

综述了生物催化主要研究方向,包括筛选新型生物催化剂、建立高通量的筛选技术平台、改造催化剂、开发新的生物催化反应类型及介质工程研究等,同时介绍了生物催化在手性技术中的应用,指出了生物催化技术存在的问题并展望未来的发展方向。     

工业生物催化过程的发展及其展望

综述了近年来工业生物催化过程的发展,提出按照生物催化剂的制备和催化过程的特点将工业生物催化分成生长耦联型催化和生长非耦联型催化,通过这两类生物催化成功的范例以及研究进展讨论生物催化工业化的途径和方法及进一步发展的方向和对策.     

Aromatic Halogenation by Using Bifunctional Flavin Reductase–Halogenase Fusion Enzymes

The remarkable site selectivity and broad substrate scope of flavin-dependent halogenases (FDHs) has led to much interest in their potential as biocatalysts. Multiple engineering efforts have demonstrated that FDHs can be tuned for non-native substrate scope and site selectivity. FDHs have also proven useful as in vivo biocatalysts and have been successfully incorporated into biosynthetic pathways to build new chlorinated aromatic compounds in several heterologous organisms. In both cases, reduced flavin cofactor, usually supplied by a separate flavin reductase (FR), is required. Herein, we report functional synthetic, fused FDH-FR proteins containing various FDHs and FRs joined by different linkers. We show that FDH-FR fusion proteins can increase product titers compared to the individual components for in vivo biocatalysis in Escherichia coli.     

离子液体在全细胞催化中的应用

离子液体作为一种新型的非水生物催化溶剂,由于其特有的性质有可能取代传统有机溶剂,并在有机化学、食品工业、新能源等领域中得到应用。介绍了离子液体在全细胞催化中的应用,着重介绍了离子液体在全细胞催化合成有机物、生物柴油制备和原位萃取3方面的应用,并阐述了将离子液体应用于全细胞催化所面临的问题。     

Sulfur removal from coal through multiphase media containing biocatalysts

A novel bioprocess using micelle biocatalysts was developed to minimize several disadvantages of conventional microbial coal desulfurization processes. The multiphase biocatalysis process consists of an organic medium (mineral oil or a mixture with n-heptane), a surfactant and an aqueous phase containing Thiobacillus ferrooxidans organisms or their cell-free enzyme extracts. Water-in-oil emulsion and reverse micelle processes have been successful for removing sulfur from bituminous coal. The preliminary results indicated that, in the case of water-in-oil emulsion, the process that used the cell-free enzyme extracts of T. ferrooxidans showed higher sulfur reduction than that containing whole cells, and reverse micells were more effective than water-in-oil emulsion. With a high concentration of bacteria, more than 50% total sulfur removal was achieved through the reverse micelle system. These results indicate that multiphase biocatalysis may have a significant potential for developing biotechnical coal desulfurization processes.     

生物催化在化妆品工业上的应用进展

生物催化是精细化工和制药工业有用的工具。提到生物催化,我们通常会想到外消旋物的动力学拆分和手性合成。化妆品行业上已经建立了生物催化过程来生产如十六烷基蓖麻醇酸酯等化妆品工业中应用的酯。尽管生物催化已经建立,但因为可供利用的商业酶还很少,所以仍然只作为工业上应用的众多催化方法之一。     

Cellular Biocatalysts Using Synthetic Genetic Circuits for Prolonged and Durable Enzymatic Activity

Cellular biocatalysts hold great promise for the synthesis of difficult to achieve compounds, such as complex active molecules. Whole-cell biocatalysts can be programmed through genetic circuits to be more efficient, but they suffer from low stability. The catalytic activity of whole cells decays under stressful conditions, such as prolonged incubation times or high temperatures. In nature, microbial communities cope with these conditions by forming biofilm structures. In this study, it is shown that the use of biofilm structures can enhance the stability of whole-cell biocatalysts. We employed two different strategies to increase the stability of whole-cell catalysts and decrease their susceptibility to high temperature. In the first approach, the formation of a biofilm structure is induced by controlling the expression of one of the curli component, CsgA. The alkaline phosphatase (ALP) enzyme was used to monitor the catalytic activity of cells in the biofilm structure. In the second approach, the ALP enzyme was fused to the CsgA curli fiber subunit to utilize the protective properties of the biofilm on enzyme biofilms. Furthermore, an AND logic gate is introduced between the expression of CsgA and ALP by toehold RNA switches and recombinases to enable logical programming of the whole-cell catalyst for biofilm formation and catalytic action with different tools. The study presents viable approaches to engineer a platform for biocatalysis processes.     

Prospects for application of enzymatic interesterification of oils in the production of modified fats

This review discusses a recent state of research in the field of enzymatic biocatalysis in application for the production of modified food fats. Properties of biocatalysts for enzymatic interesterification both been currently under development and already applied in industry of vegetable oils are discussed. The main directions of research on development of new biocatalysts, including those based on the novel recombinant lipase enzymes, as well as the potential of targeted modifications in the composition of oils by optimization of the catalytic process are covered. The relevant analysis of the enzymatic interesterification of oils shows its potential for development of energy efficient and environmentally friendly processes for production of the high quality food products with the specified characteristics.