MODIFICATION OF FATS AND OILS BY LIPASES

Enzymatic modification of fats and oils using lipases has recently come into limelight, giving rise to a breakthrough in modification technology. This paper describes the latest development and future trend of this new technology with respect to the enzyme lipases, lipase reactions, and bioreactor systems. Particular attention is paid to the utilization of this technology in industrial production of functional fats and oils. A new topic of the reasearch work of an enzymatic reaction of conversion from diglycerides to triglycerides in crude palm olein is presented in detail.     

Fuel ethanol production from corn fiber current status and technical prospects

Corn fiber, which consists of about 20% starch, 14% cellulose, and 35% hemicellulose, has the potential to serve as a low cost feedstock for production of fuel ethanol. Currently, the use of corn fiber to produce fuel ethanol faces significant technical and economic challenges. Its success depends largely on the development of environmentally friendly pretreatment procedures, highly effective enzyme systems for conversion of pretreated corn fiber to fermentable sugars, and efficient microorganisms to convert multiple sugars to ethanol. Several promising pretreatment and enzymatic processes for conversion of corn fiber cellulose, hemicellulose, and remaining starch to fermentable sugars were evaluated. These hydrolyzates were then examined for ethanol production in bioreactors, using genetically modified bacteria and yeast. Several novel enzymes were also developed for use in pretreated corn fiber saccharification. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.     

Recent development of monolithic materials as matrices in microcolumn separation systems

This review summarizes the development of monolithic materials, including both organic and inorganic polymers, according mainly to the papers published in the past two years. Due to their good permeability, fast mass transfer, high stability, and their ease of modification, such materials have been widely used in microcolumn separation systems, not only as stationary phases for CEC and capillary HPLC, but also as substances for sample concentration and enzyme reactor. All the research results demonstrate that monolithic materials in microseparation systems can be expected to play an increasingly important role in the analysis of complex samples.     

酶生物传感器中酶的固定化技术

综述了近年来国内外酶生物传感器的进展,介绍了制作酶生物传感器的关键技术——酶的固定化。固定化方法主要有吸附法、包埋法、共价键合法和交联法。固定化材料分为无机材料、有机聚合物材料、凝胶以及生物材料等。探讨了固定化方法和固定化材料对酶的固定化及酶生物传感器性能的影响,并结合自己的工作展望了酶生物传感器的发展方向和趋势。     

Recent advances in immobilized enzymatic reactors and their applications in proteome analysis

Immobilized enzymatic reactors recently have drawn much attention because of the striking advantages, such as high substrate turnover rate and ease in coupling with the separation and detection systems. Carrier materials, which have great effects on the development of the immobilized enzymatic reactors, have always being the focus of study. In this paper, the contributions, mainly in the last 5 years, on the enzymatic reactors and their applications in proteome study are reviewed, with some newly developed inorganic and organic carriers for enzyme immobilization described in details. Moreover, the hyphenation of immobilized enzymatic reactors with the separation and identification systems is also summarized. By reviewing these achievements, it could be seen that enzymatic reactors have very bright future, especially in proteome analysis.     

Microfibrillated cellulose and new nanocomposite materials: a review

Due to their abundance, high strength and stiffness, low weight and biodegradability, nano-scale cellulose fiber materials (e.g., microfibrillated cellulose and bacterial cellulose) serve as promising candidates for bio-nanocomposite production. Such new high-value materials are the subject of continuing research and are commercially interesting in terms of new products from the pulp and paper industry and the agricultural sector. Cellulose nanofibers can be extracted from various plant sources and, although the mechanical separation of plant fibers into smaller elementary constituents has typically required high energy input, chemical and/or enzymatic fiber pre-treatments have been developed to overcome this problem. A challenge associated with using nanocellulose in composites is the lack of compatibility with hydrophobic polymers and various chemical modification methods have been explored in order to address this hurdle. This review summarizes progress in nanocellulose preparation with a particular focus on microfibrillated cellulose and also discusses recent developments in bio-nanocomposite fabrication based on nanocellulose.     

Fungal Cellulase/Xylanase Production and Corresponding Hydrolysis Using Pretreated Corn Stover as Substrates

Three pretreated corn stover (ammonia fiber expansion, dilute acid, and dilute alkali) were used as carbon source to culture Trichoderma reesei Rut C-30 for cellulase and xylanase production. The results indicated that the cultures on ammonia fiber expansion and alkali pretreated corn stover had better enzyme production than the acid pretreated ones. The consequent enzymatic hydrolysis was performed applying fungal enzymes on pretreated corn stover samples. Tukey’s statistical comparisons exhibited that there were significant differences on enzymatic hydrolysis among different combination of fungal enzymes and pretreated corn stover. The higher sugar yields were achieved by the enzymatic hydrolysis of dilute alkali pretreated corn stover.     

Site-selective surface modification using enzymatic soft lithography

Surface modification with functional polymers or molecules offers great promise for the development of smart materials and applications. Here, we describe a versatile and easy-to-use method of site-selective surface modification based on the ease of microcontact printing and the exquisite selectivity of enzymatic degradation. A micropatterned poly-L-lysine (PLL) layer on solid substrates was prepared by enzymatic degradation using trypsin enzyme immobilized on a prestructured poly(dimethlylsiloxane) (PDMS) stamp. After the enzymatic degradation of PLL and the removal of the degradation products, very well defined patterning was revealed over a large scale by fluorescence microscopy and atomic force microscopy (AFM). We investigate the advantage of our method by comparison with traditional microcontact printing and found that lateral diffusion was reduced, yielding a more accurate reproduction of the master. We also demonstrate that the stamp can be reused without reinking. The patterned surface was used for site-selective modification. The strategy was applied to two applications: the first is dedicated to the creation of amino-silane patterned surfaces, and the second illustrates the possibility of patterning polyelectrolyte multilayered thin films.     

酶促不对称催化手性合成系统研究进展

正手性化合物由于具有特殊的立体结构,其对映体常表现出不同的物理化学特性和生理活性,近年来在新材料开发、新药设计、精细化学品合成等领域中发挥重要作用.手性化合物的传统制备方法是化学法,即利用手性配体或前体和催化剂(常为过渡金属)等来进行不对称合成.但由于这些方法存在试剂昂贵、反应条件苛刻(高温高压与强酸强碱)、光学纯度低等缺点,难于适应实际工业生产的要求[1].与传统化学合成法相比,生物酶法不对     

整体材料研究进展及其在微柱分析领域中的应用

整体材料具有通透性好、传质速度快、性能稳定而且容易制作等优点。它不仅可以作为微柱液相色谱和毛细管电色谱的固定相,而且也可用作样品富集和酶反应器的载体。目前,整体材料已受到越来越多的关注,并被广泛应用于各个领域。本文对近两年有机基质和无机基质整体材料的研究进展及其在微柱分析领域中的应用进行了系统的综述。     

Engineering of glucose oxidase for direct electron transfer via site-specific gold nanoparticle conjugation

Optimizing the electrical communication between enzymes and electrodes is critical in the development of biosensors, enzymatic biofuel cells, and other bioelectrocatalytic applications. One approach to address this limitation is the attachment of redox mediators or relays to the enzymes. Here we report a simple genetic modification of a glucose oxidase enzyme to display a free thiol group near its active site. This facilitates the site-specific attachment of a maleimide-modified gold nanoparticle to the enzyme, which enables direct electrical communication between the conjugated enzyme and an electrode. Glucose oxidase is of particular interest in biofuel cell and biosensor applications, and the approach of "prewiring" enzyme conjugates in a site-specific manner will be valuable in the continued development of these systems.     

Controlling membrane permeability with bacterial porins: application to encapsulated enzymes

Recent achievements of membrane protein science allow easy protein modification by genetic engineering and, for some proteins, their production in large quantities. We regard these features as the basic requirements for applications of membrane proteins in materials science. Here, we demonstrate a possible application of membrane proteins, inserting porins from the outer cell wall of Escherichia coli into the walls of liposomes. Encapsulation of enzymes into liposomes or polymer nanocapsules protects them against proteases and denaturation. Functional reconstitution of porins into the capsule shell allows to control the rate and selectivity of substrate permeation, and thus to control the enzyme reaction kinetics. We suggest that this technique can prove to be useful in the area of biosensors, providing enzymatic stability while keeping the functionality or even enhancing the sensitivity by substrate preselection. Another application of this kind of stabilisation is in the field of single enzyme activity recording.     

Enzymatic hydrolysis of high-moisture corn fiber pretreated by afex and recovery and recycling of the enzyme complex

Corn fiber is a grain-processing residue containing significant amounts of cellulose, hemicellulose, and starch, which is collected in facilities where fuel ethanol is currently manufactured. Preliminary research has shown that corn fiber (30% moisture dry weight basis [dwb]) responds well to ammonia-fiber explosion (AFEX) pretreatment. However, an important AFEX pretreatment variable that has not been adequately explored for corn fiber is sample moisture. In the present investigation, we determined the best AFEX operating conditions for pretreatment of corn fiber at high moisture content (150% moisture dwb). The optimized AFEX treatment conditions are defined in terms of the moisture content, particle size, ammonia to biomass ratio, temperature, and residence time using the response of the pretreated biomass to enzymatic hydrolysis as an indicator. Approximate optimal-pretreatment conditions for unground corn fiber containing 150% (dwb) moisture were found to be: temperature, 90?C; ammonia: dry corn fiber mass ratio, 1:1; and residence time 30 min (average reactor pressure under these conditions was 200 pounds per square inch [psig]). Enzymatic hydrolysis of the treated corn fiber was performed with three different enzyme combinations. More than 80% of the theoretical sugar yield was obtained during enzymatic hydrolysis using the best enzyme combination after pretreatment of corn fiber under the optimized conditions previously described. A simple process for enzyme recovery and reuse to hydrolyze multiple portions of AFEX-treated corn fiber by one portion of enzyme preparation is demonstrated. Using this process, five batches of fresh substrate (at a concentration of 5% w/v) were successfully hydrolyzed by repeated recovery and reuse of one portion of enzyme preparation, with the addition of a small portion of fresh enzyme in each subsequent recycling step.     

非水介质中酶催化的反应研究新进展

介绍了非水介质中酶催化反应有机合成中的应用及手性化合物的酶促拆分与合 成反应，分析了冷冻干燥保护剂和修饰剂对酶性质的影响，论述了固定化酶在有机 溶剂中的应用，并讨论了影响固定化酶性质的因素。     

淀粉衍生物的研究及应用

简要介绍了淀粉的结构和特点,以及物理改性、化学改性和酶法改性的基本原理,着重介绍了化学改性的基本原理,详细介绍了氧化淀粉、醚化淀粉和酯化淀粉的制备及应用,并对淀粉衍生物的研究方向作了展望,认为复合改性淀粉是未来淀粉化学品的发展趋势。淀粉衍生物可广泛应用于食品、纺织、造纸、医药等众多领域,具有广阔的发展前景。     

A review to recent developments in modification of carbon fiber electrodes

The unique properties of carbon fiber electrodes (CFEs) offer a number of particular advantages for their use in analytical applications. However, some pretreatment is usually necessary for the modification of the carbon surface. One of these methods is enzyme modification, that enzyme reactions in the surface of the electrode can be useful for the certain determinations. Also application of nanoparticles is very useful for modification and gives very interesting responses for the electrode in the determination of various analytes. Electrochemical oxidation of a carbon surface is one of the other methods for modification. With this work the morphology of the surface changes as well as increasing the coverage by various oxygen-containing functional groups. These groups can then interact and bind with other species introduced to the surface. The modification of the surface of carbon fiber electrodes is an interesting topic with many applications in the fields of analytical chemistry, environmental and health science, fuel cell and biofuel cell and many others. In this review article we discussed about the various modification methods for carbon fiber electrodes and applications of these CFEs.     

Ammonia Fiber Expansion (AFEX) Pretreatment,Enzymatic Hydrolysis,and Fermentation on Empty Palm Fruit Bunch Fiber (EPFBF) for Cellulosic Ethanol Production

Empty palm fruit bunch fiber (EPFBF), a readily available cellulosic biomass from palm processing facilities, is investigated as a potential carbohydrate source for cellulosic ethanol production. This feedstock was pretreated using ammonia fiber expansion (AFEX) and enzymatically hydrolyzed. The best tested AFEX conditions were at 135 °C, 45 min retention time, water to dry biomass loading of 1:1 (weight ratio), and ammonia to dry biomass loading of 1:1 (weight ratio). The particle size of the pretreated biomass was reduced post-AFEX. The optimized enzyme formulation consists of Accellerase (84 μL/g biomass), Multifect Xylanase (31 μL/g biomass), and Multifect Pectinase (24 μL/g biomass). This mixture achieved close to 90% of the total maximum yield within 72 h of enzymatic hydrolysis. Fermentation on the water extract of this biomass affirms that nutrients solely from the pretreated EPFBF can support yeast growth for complete glucose fermentation. These results suggest that AFEX-treated EPFBF can be used for cellulosic biofuels production because biomass recalcitrance has been overcome without reducing the fermentability of the pretreated materials.     

A simplified modification of the AOAC official method for determination of total dietary fiber using newly developed enzymes

Since 1985, AOAC Method 985.29 has been globally adopted as a standard method for determination of total dietary fiber in foods. Nevertheless, an aspect of AOAC Method 985.29 that needs to be improved is the laborious process to treat 3 enzymes separately at their individual proper pH, which is quite time-consuming. Several examinations have been carried out to resolve this problem. The characteristics of newly developed thermostable alpha-amylase, neutral protease, and amyloglucosidase were evaluated based on the pH-activity profile and the property of starch hydrolysis in comparison with those of the conventional enzyme reagents. These 3 developed enzymes were found to work under the same pH condition and to accomplish sufficient digestion for the typical 3 starches: soluble starch, corn starch, and wheat starch. The experimental results revealed that the dietary fiber determination in foods could be performed without pH adjustment in the enzymatic digestion process. The modified method will be greatly helpful in determining the total dietary fiber contents in food materials with less laborious work and with an accuracy equivalent to that of AOAC Method 985.29.     

CHEMOENZYMATIC FUNCTIONALIZATION OF RIBONUCLEIC ACID WITH AZOBENZENE CHROMOPHORES

In recent years, biological molecules have brought about a renaissance in the development of novel responsive materials. An example of this is the development of new photoresponsive materials for the artificial regulation of chemical and biological systems. Towards this we have developed a novel enzymatic synthetic approach for covalent attachment of photoresponsive units into the RNA backbone. This involves a lipase catalyzed acylation of the 2' hydroxyl group in the ribose sugars in the RNA molecule to incorporate photo-isomerizable azobenzene groups into the RNA strands. A reverse micellar approach was used for this RNA functionalization to maintain the solubility of the nucleic acid as well as to limit the preferred hydrolysis reaction in aqueous media. The azobenzene groups incorporated in the RNA molecule show photo-isomerization behavior and can serve as optical ‘handles’ for the manipulation of the conformation of RNA. This modification of RNA using covalently attached chromophores or fluorophores is a generic approach that can be extended to other biomacromolecular matrices leading to new opportunities for biophotonic device applications.

     

典型高分子纤维发展回顾与未来展望

高分子纤维作为发展国民经济的基础材料、国防军工的战略材料、新兴产业的前沿材料,其产品内涵与应用领域正在不断拓展.本文首先简要介绍了国内外高分子纤维材料的发展简史,其依次经历了天然纤维、人造纤维、合成纤维(差别化、功能化、高性能等纤维)等发展阶段.其次,结合本课题组相关工作重点阐述了通用型聚酯纤维、高性能聚苯硫醚纤维以及生物质聚乳酸纤维等典型高分子纤维材料的研究进展,包括发展历程、制备方法、性能优化、应用领域等内容.最后,展望了高分子纤维材料的发展趋势,我们认为基于材料、信息、生物、机械等学科交叉融合与技术突破,具有多材料、多结构、多功能的绿色、超性能、智能纤维材料将成为未来发展方向.