海洋寡聚糖对仔猪生产性能及血液理化指标的影响

选择0-35日龄200头哺乳仔猪和35-70日龄160头断乳仔猪各分为对照组和寡聚糖组,每组10个重复,各重复仔猪数相等。研究探讨了海洋寡聚糖作为猪饲料添加剂对生产性能及血液理化指标的影响。结果表明：寡聚糖组与对照组相比,0-35日龄哺乳仔猪和35-70日龄保育期仔猪的死亡率、次品率均显著降低（P〈0．05）,而平均体重分别提高18％和14．2％,显著高于对照组（P〈0．05）;寡聚糖组白细胞、粒细胞、红细胞、血红蛋白、压积有减少的倾向,而淋巴细胞和血小板含量增加,但差异都不显著。与对照组相比寡聚糖组谷草转氨酶、谷丙转氨酶、碱性磷酸酶及乳酸脱氢酶的活力略有降低,谷草/谷丙比和乎谷氨酰转肽酶的活性呈上升趋势,但差异均不显著。寡聚糖组的肌酐含量比对照组显著增加外（P〈0．05）,其余尿酸、葡萄糖、甘油三脂、高密度脂蛋白胆固醇、球蛋白、载脂蛋白A1的含量均下降,而尿素、胆固醇、低密度脂蛋白胆固醇、白蛋白、总蛋白含量比对照组略有增加的趋势,但差异均不显著。     

壳寡聚糖对变形链球菌乳酸脱氢酶及γ谷丙转氨酶的影响

目的 研究壳寡聚糖对变形链球菌乳酸脱氢酶（LDH）及γ谷丙转氨酶（γ-GT）的影响。方法 将变形链球菌接种在含壳寡聚糖的培养基中,测定培养上清液中乳酸脱氢酶及γ谷丙转氨酶等细胞内酶的含量。结果 菌液上清中的LDH和γ-GT2种细胞内酶含量显著高于空白对照组。表明接种在含壳寡聚糖培养基中的细菌出现了明显的细胞内酶溢出,并与浓度相关。结论 壳寡聚糖对细菌的细胞壁有破坏作用,可能是壳寡聚糖具有防龋功能的原因。     

植物凝集素的分子生物学研究

植物凝集素是一类具有高度特异性糖结合活性的蛋白,含有一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,主要生理功能是介异植物的防御反应。到目前为止已克隆了２２２个植物凝集素基因。作者就植物凝集素的分类、性质、功能、凝集素基因的克隆和凝集素的翻译后加工过程作一综述。     

功能糖的免疫调节作用

功能糖是世界新兴的朝阳产业,是健康产业的重要原料。所谓功能糖,是指以功能性低聚糖、功能性糖醇、功能性膳食纤维为主要代表的具有营养保健功能的糖类。它们不但能促进双歧杆菌的增殖,有益于肠道健康。而且具有低热值、稳定、安全无毒、黏度大、吸湿性强等理化特性以及具有改善肠道微生物区系、降低血清胆固醇和中性脂肪含量、改善血糖含量、提高饲料利用效率等生理功能。最近,研究人员又发现功能糖还具有提高人体和动物的免疫机能的功效,更是引起了人们的关注。     

寡聚半乳糖醛酸对2,4-D引起的黄瓜下胚轴伸长的抑制(简报)

10多年来的研究认为寡聚糖作为信号分子激发了植物的抗病基因的表达,如能调节生产植物蛋白酶抑制物和植保素,触发过敏反应。近期研究还发现寡聚糖具有调节植物生长、发育的功能,这些具有调节功能的寡     

香菇不同发育阶段子实体多糖的理化性质及体外免疫活性研究

香菇多糖是从香菇菌丝体或子实体中提取纯化得到的高分子葡聚糖,作为香菇主要的生物活性物质,具有提高免疫力、抗病毒、抗氧化和抗真菌等生物活性。本研究对幼菇期、菌褶期、采收期、成熟期和开伞期5个不同发育阶段香菇粗多糖含量、理化性质和体外免疫活性进行比较分析。结果表明,其粗多糖含量、理化性质和体外免疫活性具有明显差异。粗多糖得率呈现先增加后降低的趋势,菌褶期得率最高;粗多糖含量也呈现先增加后降低的趋势,成熟期含量最高;多糖的分子量因发育期不同而有较大差异,发育后期所得粗多糖分子量千万级以上组分的比例增加,分子量百万级和十万级的多糖组分比例降低;不同发育阶段香菇子实体多糖的单糖组成均包含果糖、半乳糖、葡萄糖和甘露糖4种单糖,且都以葡萄糖为主;5个阶段的多糖组分均有较好的体外免疫活性,其中幼菇期粗多糖在浓度500μg/mL时表现出最高的体外免疫活性。本研究探讨了香菇不同发育阶段子实体多糖的理化性质及体外免疫活性,为香菇采收期的确定及香菇多糖的制备与利用提供理论依据。     

甘露寡糖分离纯化研究进展*

甘露寡糖具有润肠通便、降血脂、抗结肠炎症、增强免疫及调节肠道菌群等生理功能,在食品药品等领域具有广阔的应用前景。水解法制得的甘露寡糖含有单糖、未分解聚糖、不同聚合度寡糖及盐离子等杂质,还需要进一步分离纯化。综述了近年来国内外甘露寡糖的主要纯化方法包括柱层析法、膜分离法、乙醇沉淀法和微生物发酵法等。总结了各种方法的原理、应用范围和应用实例,并对不同方法的优缺点进行了分析。     

甘露寡糖分离纯化研究进展*

甘露寡糖具有润肠通便、降血脂、抗结肠炎症、增强免疫及调节肠道菌群等生理功能,在食品药品等领域具有广阔的应用前景。水解法制得的甘露寡糖含有单糖、未分解聚糖、不同聚合度寡糖及盐离子等杂质,还需要进一步分离纯化。综述了近年来国内外甘露寡糖的主要纯化方法包括柱层析法、膜分离法、乙醇沉淀法和微生物发酵法等。总结了各种方法的原理、应用范围和应用实例,并对不同方法的优缺点进行了分析。     

多糖裂合酶及其应用前景

多糖裂合酶(polysaccharidelyase,PL)是一类由原核或真核生物产生的、作用于多糖的降解酶。大多数PL的底物为带负电荷的多糖,它们通过β-消去机制作用于1→4糖苷键,最终产物为不饱和的寡聚糖。PL降解多糖可产生具有新颖理化性质的寡聚物,这为多糖的研究和应用提供了新途径。     

碱性木聚糖酶研究进展*

木聚糖是一种在自然界中含量仅次于纤维素的丰富的可再生资源,木聚糖酶是一类可以将木聚糖水解成单糖和寡糖的酶,利用木聚糖酶将木聚糖分解后的产物被广泛应用于食品、造纸以及纺织等行业。木聚糖酶按其对酸碱环境的耐受能力分为碱性木聚糖酶、中性木聚糖酶和酸性木聚糖酶,其中碱性木聚糖酶适合应用于造纸工业中,尤其在造纸的制浆、促进漂白及废纸脱墨等多种工艺中,可以显著提高纸张质量,有效降低氯气排放量,从而减少对环境的污染。随着生物技术的进步,利用基因工程技术可以对碱性木聚糖酶进行分子改造,以提高其耐碱、耐热能力,扩大其在工业应用中的条件范围。介绍碱性木聚糖酶在分子改造方面的研究进展以及其在造纸漂白和制浆、废纸脱墨中的应用。     

寡聚糖诱导的植物抗性信号转导

来源于植物及其病原体细胞壁的寡聚糖,可作为激发子诱导植物细胞发生抗性反应,寡聚糖信号被植物细胞识别后,可迅速引起质膜去极化,离子通道开放,胞外培养基碱化等瞬间反应;还可通过硬脂酸代谢途径合成茉莉酸信号分子,诱导抗性相关基因的表达。     

Chemoenzymatic synthesis of 6omega -modified maltooligosaccharides from cyclodextrin derivatives

Regioselectively substituted maltooligosaccharides were prepared by enzymatic transformation of modified cyclodextrins by using simultaneously two different enzymes: cyclodextrin glucanotransferase (CGTase) and amyloglucosidase. Oligosaccharides were obtained in very good yields and their structures were identified by 1D and 2D NMR spectroscopy. These results provided new information about the specificity of the catalytic sites of CGTase and amyloglucosidase. They also offered new ways for the synthesis of regioselectively modified maltooligosaccharides.     

Immunochemical studies on blood groups. Structures and immunochemical properties of nine oligosaccharides from B-active and non-B-active blood group substances of horse gastric mucosae.

Oligosaccharides from base-borohydride-treated B-active and non-B-active glycoproteins of horse stomach mucosae were purified chromatographically on Bio-Gel P-2, charcoal-Celite, paper and high pressure liquid chromatography. From colorimetric and gas-liquid Chromatographic analyses, methylation, quantitative periodate oxidation and Smith degradation, structures of nine Oligosaccharides are proposed. Seven have not been previously described. The oligosaccharide isolated in largest amount in the B-active reduced tetrasaccharide analogous to an A-active reduced oligosaccharide from pig submaxillary mucin, and a reduced octasaccharide, the largest isolated, has two B determinants and may represent full expression of B-specific biosynthetic potential of the mucosal lining. Three B-active and one non-B-active oligosaccharide possessed the core structure previously identified in Oligosaccharides from human blood group, B, HLe^b, Le^a and precursor I substances. Two non-B-active and one B-active compound inhibited the cross reaction of type XIV horse antipneumococcal sera with blood group substances. Terminal nonreducing α-linked dGlcNAc (d-2-acetamido-2-deoxyglucopyranose), previously found in Oligosaccharides of hog blood group substances, was also present in a tetrassarcharide of the non-B-active material. Oligosaccharides released from blood group glycoproteins of horse stomach mucosae are smaller and hence less heterogeneous than those from human ovarian cyst and perhaps hog A + H and human gastric mucosae.     

病毒抗原糖基化与免疫关系的研究进展

糖基化是蛋白质的一种重要的翻译后修饰,在影响蛋白质的结构和功能方面扮演着重要角色。许多病毒抗原都有糖基化的现象,糖基化会改变病毒对宿主的免疫逃避、病毒抗原的免疫原性等。了解病毒抗原糖基化与免疫之间的关系,将有助于抗病毒疫苗的研究。     

Chemoenzymatic synthesis of oligosaccharides and glycoproteins

Oligosaccharides are involved in a wide range of biological processes including, for example, bacterial and viral infection, cancer metastasis, the blood-clotting cascade and many other crucial intercellular recognition events. The molecular details of these biological recognition events are, however, not well understood. To express their function, oligosaccharides often occur as glycoconjugates attached to proteins (called glycoproteins) or lipids (called glycolipids) that are often found on the surface of cells. Such physiological relevance has stimulated researchers to make significant advances in oligosaccharide and glycoprotein preparation despite the chemically imposing and polydisperse nature of these molecules. The chemical and Chemoenzymatic methods developed recently have facilitated the synthesis of structurally defined oligosaccharides and glycoconjugates such that a more thorough understanding of their biological function and potential therapeutic application can be addressed.     

魔芋葡甘低聚糖对小鼠抗氧化酶活性的影响

研究魔芋葡甘低聚糖对小鼠血浆和肝脏中抗氧化酶活性的影响。魔芋葡甘低聚糖能有效地降低肝脏中丙二醛(MDA)的含量,提高肝脏和血浆中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-PX)的活性。尤以高剂量组效果最好。     

糖苷合成酶——— 一类新型的寡糖高效合成工具

寡糖是哺乳动物细胞表面糖蛋白和糖脂以及微生物来源的生理活性物质的要素之一,其应用于医药的巨大潜能至今还没有得到充分体现,主要原因是合成足够于临床使用的寡糖非常困难.传统的化学法和酶法在大规模合成寡糖方面都有一定局限性.近年来,分子生物学技术大大推动了糖苷酶合成寡糖的研究,将糖苷酶催化中心亲核体氨基酸定点突变为非亲核体氨基酸,导致酶的原有水解活性丧失,只催化糖苷键合成反应,寡糖产量最高可达99%,人工产生了一类新酶——糖苷合成酶(glycosynthases),随后又产生了硫代糖苷酶(thioglycoligases)和硫代糖苷合成酶(thioglycosynthases).糖苷合成酶的高通量筛选可用双质粒系统和酵母三杂交系统进行,其活性的进一步改进可通过亲核体氨基酸位点不同氨基酸取代、其他位点氨基酸突变、反应条件优化等方法进行,其区域选择性的改变或增强可通过改变糖基受体分子达到.糖苷合成酶作为一种新型高效的生物催化剂,对寡糖的工业化合成有着重要意义,它的出现对糖生物学的发展必将起到巨大的推动作用.     

Modified oligosaccharides as potential dental plaque control materials

Metabolic acids produced by oral pathogens demineralize tooth surfaces, leading to dental caries. Glucosyltransferases are the key factor in this process. We synthesized various modified oligosaccharides and tested them for their inhibitory effects on glucosyltransferase activity. Oligosaccharides were produced using a mixed-culture fermentation of Lipomyces starkeyi and Leuconostoc mesenteroides and then further modified as iron- and sulfate-oligosaccharides. Iron- and sulfate-oligosaccharides reduced glucosyltransferase activity of Streptococci from 17% to 43% and prevented the formation of insoluble biomass on the surface of glass vials or stainless steel wires in the presence of sucrose. They also reduced the growth and acid productions of oral pathogens including S. mutans, S. sobrinus, Eikenella corrodens, Prevotella intermedia, and Actinobacillus actinomycetemcmitans.     

Accessibility of glycolipid and oligosaccharide epitopes on rabbit villus and follicle-associated epithelium

The initial step in many mucosal infections is pathogen attachment to glycoconjugates on the apical surfaces of intestinal epithelial cells. We examined the ability of virus-sized (120-nm) and bacterium-sized (1-microm) particles to adhere to specific glycolipids and protein-linked oligosaccharides on the apical surfaces of rabbit Peyer's patch villus enterocytes, follicle-associated enterocytes, and M cells. Particles coated with the B subunit of cholera toxin, which binds the ubiquitous glycolipid GM1, were unable to adhere to enterocytes or M cells. This confirms that both the filamentous brush border glycocalyx on enterocytes and the thin glycoprotein coat on M cells can function as size-selective barriers. Oligosaccharides containing terminal beta(1,4)-linked galactose were accessible to soluble lectin Ricinus communis type I on all epithelial cells but were not accessible to lectin immobilized on beads. Oligosaccharides containing alpha(2, 3)-linked sialic acid were recognized on all epithelial cells by soluble Maackia amurensis lectin II (Mal II). Mal II coated 120-nm (but not 1-microm) particles adhered to follicle-associated enterocytes and M cells but not to villus enterocytes. The differences in receptor availability observed may explain in part the selective attachment of viruses and bacteria to specific cell types in the intestinal mucosa.     

Carbohydrate binding properties of complex-type oligosaccharides on immobilized Datura stramonium lectin

The carbohydrate binding specificity of Datura stramonium agglutinin was studied by analyzing the behavior of a variety of complex-type oligosaccharides on a D. Stramonium agglutinin-Sepharose column. Oligosaccharides which contain Gal beta 1----4GlcNAc-beta 1----4(Gal beta 1----GlcNAc beta 1----2)Man units are retarded in the column so long as the pentasaccharide unit is not substituted by other sugars. Oligosaccharides which contain unsubstituted Gal beta 1----4GlcNAc beta 1----6(Gal beta 1----4GlcNAc beta 1----2)Man groups and those in which there is at least one Gal beta 1----4GlcNAc repeating unit present on an outer chain bind to the column and are eluted with buffer containing N-acetylglucosamine oligomers. Binding was not affected by the inner core portion of complex oligosaccharides nor by the presence of a bisecting N-acetylglucosamine residue. With these principles in mind, the column can be used as an effective tool for the analysis of complex-type, asparagine-linked sugar chains.