Toward automated synthesis of oligosaccharides and glycoproteins

The discovery of previously unknown functions associated with carbohydrates and the study of their structure-function relations are of current interest in carbohydrate chemistry and biology. Progress in this area is, however, hampered by the lack of convenient and effective tools for the synthesis and analysis of oligosaccharides and glycoconjugates. Development of automated synthesis of such materials is necessary to facilitate research in this field. This review describes recent advances in carbohydrate synthesis, with particular focus on developments that have potential application to the automated synthesis of oligosaccharides, glycopeptides, and glycoproteins.     

Identification of the 1H-NMR spectra of complex oligosaccharides with artificial neural networks

Artificial networks can be used to identify hydrogen nuclear magnetic resonance (1H-NMR) spectra of complex oligosaccharides. Feed-forward neural networks with back-propagation of errors can distinguish between spectra of oligosaccharides that differ by only one glycosyl residue in twenty. The artificial neural networks use features of the strongly overlapping region of the spectra (hump region) as well as features of the resolved regions of the spectra (structural reporter groups) to recognize spectra and efficiently recognized 1H-NMR spectra even when the spectra were perturbed by minor variations in their chemical shifts. Identification of spectra by neural network-based pattern recognition techniques required less than 0.1 second. It is anticipated that artificial neural networks can be used to identify the structures of any complex carbohydrate that has been previously characterized and for which a 1H-NMR spectrum is available.     

壳寡糖和几丁寡糖的制备方法及其在水产上的应用

人们期望无污染、无残留的绿色水产品。但近年来,随着水产养殖密度和规模迅速扩大,水产动物病害频发,滥用抗生素所导致的菌株耐药性等问题逐渐凸显,这给水产养殖可持续发展、绿色发展带来挑战。而壳寡糖和几丁寡糖由于无毒、无害、无残留,具有多种生物活性功能且来源广泛,逐渐被众多学者重视并研究。壳寡糖是几丁质或者壳聚糖经过酶解法、化学法或者物理法而获得的低聚糖,几丁寡糖是几丁质的降解产物或壳寡糖的乙酰化产物。目前,有关壳寡糖和几丁寡糖作为绿色的饲料添加剂、疫苗佐剂和水产品保水保鲜剂的研究已经开展,其在水产养殖中具有非常广阔的发展空间和应用前景。基于此,对壳寡糖和几丁寡糖的制备方法进行了总结,探讨了壳寡糖和几丁寡糖在水产动物饲料添加剂、疫苗佐剂和水产品保水保鲜中的应用,突出其调节水生动物免疫、促生长、抗氧化、影响鱼类体成分等方面的生物活性,以期为壳寡糖和几丁寡糖在水产上的深入研究和产业化应用提供参考。     

细菌芳香聚酮研究进展

鉴于芳香聚酮化合物在抗菌、抗肿瘤、抗病毒等方面具有重要的临床药用价值,该文综述了细菌芳香聚酮化合物及其生物合成研究的主要进展,重点讨论了四类芳香聚酮的生物活性和化学结构以及芳香聚酮生物合成机理研究的基础理论意义。在此基础上对组合生物合成新的具有一定生物活性化合物的研究前景进行了展望。     

海洋寡糖诱导植物抗逆性的研究进展

海洋寡糖是海洋多糖经过降解得到的一系列寡糖片段,具有独特的分子结构和生物学活性,作为外源诱导物对植物生长及防御反应具有一定的调节作用,是一种新型、天然的植物生长调节剂。海洋寡糖以壳寡糖、褐藻寡糖、琼胶寡糖、卡拉胶寡糖、石莼寡糖等为代表。植物细胞识别海洋寡糖信号分子后,诱发活性氧爆发,引起信号分子传导,激发相关防御基因的表达,诱导植物防御酶活性提高,合成植物抗逆物质,提高植物抗逆能力。从海洋寡糖的种类、作用机制及作用特点3方面阐述了海洋寡糖在植物抗逆诱导方面的研究进展,以期为海洋寡糖在植物抗逆方面的应用研究提供参考。     

海藻寡糖在农业领域的应用研究进展

海藻寡糖是海藻多糖经过降解得到的一系列寡糖片段,分子量低、水溶性好,具有广泛的生物活性优势,在农业生产中具有广阔的应用前景。文章对近年来海藻寡糖在土壤修复和促进植物生长两方面的研究进展进行综述,同时指出海藻寡糖对土壤重金属的不同作用效果限制了其在土壤修复中的进一步应用、土壤微生物对海藻寡糖—重金属络合物的影响机理不明及海藻寡糖作为植物诱导剂在实际应用中存在局限性等问题。因此,今后在海藻寡糖的利用中应注意以下问题:进行土壤修复时,应针对土壤的酸碱度及重金属污染情况,合理选择海藻寡糖的施用量,确定适宜的修复方式;可将海藻寡糖与其他诱导剂或杀菌剂联合使用以解决其作为诱导剂的局限性;此外,海藻寡糖可作为新型肥料添加剂进行深入开发,以促进其在农业领域的进一步应用。     

Intracellular functions of N-linked glycans

N-linked oligosaccharides arise when blocks of 14 sugars are added cotranslationally to newly synthesized polypeptides in the endoplasmic reticulum (ER). These glycans are then subjected to extensive modification as the glycoproteins mature and move through the ER via the Golgi complex to their final destinations inside and outside the cell. In the ER and in the early secretory pathway, where the repertoire of oligosaccharide structures is still rather small, the glycans play a pivotal role in protein folding, oligomerization, quality control, sorting, and transport. They are used as universal "tags" that allow specific lectins and modifying enzymes to establish order among the diversity of maturing glycoproteins. In the Golgi complex, the glycans acquire more complex structures and a new set of functions. The division of synthesis and processing between the ER and the Golgi complex represents an evolutionary adaptation that allows efficient exploitation of the potential of oligosaccharides.     

Bispora sp. MEY-1 来源嗜酸果胶甲酯酶性质分析及其应用研究

食品加工副产物富含果胶类物质，果胶酶可以将其降解为果胶低聚糖，不仅可以有效控制果胶低聚糖的聚合度及结构，还能实现食品加工副产物废弃资源的再利用，创造新的经济效益。从嗜酸真菌Bispora sp. MEY-1克隆获得一个碳水化合物第8家族的果胶甲酯酶基因Pem8A，将其连接到表达载体pPIC9上，在毕赤酵母 GS115 中实现高效异源表达。对纯化后的重组蛋白PME8A的酶学性质进行测定，发现其最适温度为60 ℃，在55～80 ℃可保持80%以上的酶活；最适pH为3.5，在pH 2.5～5.0范围内维持50%以上的酶活，是真菌来源中少数的嗜酸果胶甲酯酶。用PME8A处理苹果渣、橘皮果胶粗提物后，去甲基化效果明显，使得Achaetomium sp. Xz8来源的内切多聚半乳糖醛酸酶PG8fn酶活分别提高了8.5倍和1倍，表现出很好的协同效应。研究证明果胶甲酯酶PME8A可以应用于从食品加工副产物生产果胶寡糖，为果胶低聚糖的获取提供了新的方法。     

A pituitary N-acetylgalactosamine transferase that specifically recognizes glycoprotein hormones

The glycoprotein hormones lutropin (LH) and follitropin (FSH), which have common alpha-subunits but hormone-specific beta-subunits, are both synthesized in the gonadotroph. However, they bear Asn-linked oligosaccharides that differ in structure. Those on LH terminate with the sequence SO4-4GalNAc beta 1----4GlcNAc beta 1----2Man alpha, whereas those on FSH terminate with the sequence sialic acid alpha-Gal beta 1----4GlcNAc beta 1----2Man alpha. A GalNAc-transferase was identified in bovine pituitary membranes that recognizes features of the alpha-subunit peptide and adds GalNAc to its oligosaccharides with an apparent Michaelis constant of 25 micromolar. The different patterns of glycosylation for LH and FSH indicate that access to the protein recognition marker on the alpha-subunit is modulated by the associated beta-subunit. The tightly regulated synthesis of sulfated and sialylated oligosaccharides on the pituitary glycoprotein hormones suggests these oligosaccharides have an important biological role.     

我国海藻寡糖领域发展态势分析

海藻寡糖是来源广泛的海洋多糖的降解产物,具有抗氧化、抑菌、促进植物生长、诱导植物抗逆性等多种生物活性,开发前景广阔。以国家知识产权中国专利数据库为数据源,检索了1985-2015年期间我国海藻寡糖领域相关专利,从申请量、申请人、国际专利分类号、技术热点对海藻寡糖领域的发展态势进行分析。结果表明,从2010年开始,该领域相关专利申请量进入快速增长期;中国海洋大学在该领域技术优势明显,紧随其后的是中国海洋局第三海洋研究所、中国科学院海洋研究所;专利的技术热点主要在海藻寡糖的制备与应用两个方面,以制备为基础,对海藻寡糖在医药领域、食品与饲料添加剂、农业领域等方面的应用进行分支细化的研究。该研究结果对我国在海藻寡糖领域的发展和布局具有一定的借鉴意义。     

类胡萝卜素概述

类胡萝卜素是广泛存在于自然界中的一类色素,和人类健康密切相关。本文就类胡萝卜素的重要生物学功能、生物合成途径及影响其合成的相关合成酶基因的研究进展作一概要综述。     

植物次生代谢产物异黄酮的调控机理

异黄酮是豆类植物体内形成的一类次生代谢产物。它主要参与组织和病源微生物的互作及防御反应，具有诱导根瘤菌结瘤、抗病源菌、抗雌激素、抗氧化、抗溶血等生理功能，特别是在人类抗肿瘤活性方面具有十分重要作用而受到人们的普遍关注。本文从异黄酮的结构和功能、调控路径及关键酶等方面综述了异黄酮在豆类和非豆类植物中的研究概况。通过转基因的方法探讨非豆类植物包括单子叶和双子叶植物的异黄酮合成和调控水平，为有目的调控异黄酮在不同组织中的含量提供理论依据。     

Templating three-dimensional self-assembled structures in bilayer block copolymer films

The registration and alignment of a monolayer of microdomains in a self-assembled block copolymer thin film can be controlled by chemical or physical templating methods. Although planar patterns are useful for nanoscale device fabrication, three-dimensional multilevel structures are required for some applications. We found that a bilayer film of a cylindrical-morphology block copolymer, templated by an array of posts functionalized with a brush attractive to the majority block, can form a rich variety of three-dimensional structures consisting of cylinder arrays with controllable angles, bends, and junctions whose geometry is controlled by the template periodicity and arrangement. This technique allows control of microdomain patterns and the ability to route and connect microdomains in specific directions.     

Evidence for a malarial parasite interaction site on the major transmembrane protein of the human erythrocyte

Soluble oligosaccharides derived from the surface of human erythrocytes were tested for their ability to competitively inhibit invasion of erythrocytes by Plasmodium falciparum, a malarial parasite. Invasion was most effectively inhibited by erythroglycan, a carbohydrate component of the band 3 transmembrane protein. The lactosamine chains of erythroglycan contributed much of the inhibitory activity. This indication of a primary parasite interaction site on band 3 supports a role for this protein in mediating the radical alterations of the erythrocyte cytoskeleton that accompany invasion.     

细菌Ⅲ型聚酮合酶研究进展

Ⅲ型聚酮合酶（PKS）被认为是结构最简单的聚酮合酶,这一类酶广泛存在于植物细菌和真菌中。随着基因组学的发展,细菌中Ⅲ型聚酮合酶引起越来越多的关注。Ⅲ型聚酮合酶在不同细菌中表现出不同的功能,其产物的结构和生物学活性也各不相同。对细菌Ⅲ型聚酮合酶的生物工程学改造也一直是研究的热点。综述了目前已经完成功能鉴定的细菌Ⅲ型聚酮合酶的研究进展,按照细菌Ⅲ型聚酮合酶产物的不同将其分为五类,并分别论述了各类细菌Ⅲ型聚酮合酶的结构、功能以及特点,对深入研究不同细菌Ⅲ型聚酮合酶以及进行生物工程学改造具有重要意义。     

甜玉米遗传育种研究进展

甜玉米是玉米的一种胚乳突变型，甜玉米根据乳熟期胚乳中糖分含量和WSP含量的多少分为普通甜玉米、超甜玉米和加强甜玉米，加强甜玉米又称超甜粘玉米。目前在甜玉米育种中常用的基因有sul、sh2、se、btl、bt2、ae、wx、du等，它们都与胚乳碳水化合物代谢有关。这些基因的单基因纯合或多基因互作都能引起胚乳中碳水化合物组成或含量的改变。目前，已定出了与甜玉米有关的主要胚乳突变基因在玉米染色体上的确切位置，而且对这些基因在胚乳碳水化合物合成途径中的作用也有了较深入的了解。     

植物凝集素及其在抗虫基因工程中的应用

植物凝集素是一类具有高度特异性糖结合活性的蛋白,含有1个或多个可与单糖或寡聚糖特异可逆结合的非催化结构域。它的糖结合特异性主要针对外源寡糖,主要生理功能是介导植物的防御反应,在农业、医学等领域应用前景广阔。综述了植物凝集素的分子生物学的研究进展,介绍了植物凝集素的分类、性质、结构、功能,以及在抗虫基因工程中的应用。     

Estimating the Nutrient Balance of Multicomponent Meat Products Using Information Technologies

A computer system for the quality and nutrient balance assessment of multicomponent meat products, which is used for calculating the quantitative and qualitative indicators of food products, has been examined. In the computer system, the amino acid qualitative composition is determined by the comparative redundancy factor, the amino acid composition differences, the utility, and the biological value. The main block of the computer system is the Food Product Chemical Composition general reference database, which consists of five subblocks: the amino acid, fatty acid, carbohydrate, vitamin, and mineral composition datasets. In order to develop the database, the object-oriented environments with the application of the Delphi- 7 desktop relational database management system are used. The second main block of the computer system is the Product Design block. An example of the computer system operation to assess the quality of the amino acid balance in the emulsified meat products (small sausages) is given. Four-percent soy protein incorporated into the formulation has been shown to change the main raw material composition (decreasing the secondgrade trimmed beef content from 48 to 35% and the semifat pork content from 30 to 23%). No significant change in the amino acid composition, the biological value (comprising 90.7 and 89.58% before and after adding, respectively), the amino acid score difference factor (comprising 9.3 and 10.43% before and after adding, respectively), the comparative redundancy factor (comprising 0.33 and 0.38 unit fractions, respectively), and the utility (9.16 and 9.04 unit fractions, respectively) has been revealed.     

寡糖农药作用机理及生物来源研究进展

介绍了寡糖生物农药的作用机理,分析了寡糖种类及来源,研究了黄原胶寡糖的生物活性。     

植物黑色素的研究进展

植物黑色素是一类具有复杂化学结构的大分子物质,在食品、药品、化妆品等行业有潜在的应用价值。本文对近年来植物黑色素的提取工艺、理化性质、结构归属、生理功能等进行了详细阐述,并对植物黑色素的研究趋势进行了展望。