New Insights into the Structure of Kappa/Beta-Carrageenan: A Novel Potential Inhibitor of HIV-1

New insights into the structure of the hybrid κ/β-carrageenan (κ/β-CRG) of the red alga Tichocarpus crinitus have been obtained. Carrageenan oligosaccharides were prepared through the chemical and enzymatic depolymerization of κ/β-CRG with κ-carrageenase and its the enzyme-resistant fraction. The composition and distribution of the repetition units of κ/β- CRG were investigated by using the negative ion tandem MALDI-TOFMS and ESIMS method, which made it possible to prove and characterize the hybrid structure of this polysaccharide. An analysis revealed the blockwise distribution of the long β-blocks along the polysaccharide chain, with the inclusion of κ/β, μ/ν-blocks and some ι-blocks. Furthermore, the desulfated κ/β-CRG was shown to contain of –G–D– repeating units up to 3.5 kDa. Previous studies have demonstrated that CRGs suppress the replication of several viruses. Here, we established that κ/β-CRG and its oligosaccharides significantly inhibit the transduction efficiency of replication-defective lentiviral particles pseudotyped with the envelope proteins of three different viruses. We found that the polysaccharide and its oligosaccharides strongly reduced the transduction efficiency of lentiviral particles pseudotyped with GP160—the envelope protein of the human immunodeficiency virus HIV-1—when added to T-lymphocyte Jurkat cells. The CRG oligosaccharides displayed significantly higher antiviral activity.     

体外模拟发酵探究KGM和KOS与不同胃肠段微环境的影响

不同胃肠段微环境对机体健康的影响及其与膳食纤维的相互作用是目前研究的热点。该文为探究魔芋葡甘聚糖(konjacglucomannan,KGM)和魔芋葡甘低聚糖(konjac oligosaccharides,KOS)与不同胃肠段微环境的影响,分别以KGM和KOS为碳源,采用YCFA培养基培养不同胃肠段微生物,同时做葡萄糖(glucose)和不加碳源的空白对照,测定不同发酵液pH值、黏度、菌落总数、短链脂肪酸(short-chain datty acids,SCFAs)、总糖及还原糖含量。与对照相比,随着发酵时间的延长,添加KGM和KOS的发酵液pH降低,SCFAs含量增加,菌落总数增加;KGM显著增加胃及小肠发酵液黏度,总糖和还原糖含量略有降低,大肠发酵液中还原糖含量先增加后减少。KGM和KOS可调节不同胃肠段发酵液环境,增加微生物数量及代谢产物含量,从而更有利于机体健康,为KGM和KOS的应用提供新思路。     

稀碱液中大豆低聚糖的溶出举动

经研究发现在稀碱液中大豆低聚糖的浸出率明显提高,大豆的最大吸水率也有显著增加,并发现低聚糖的浸出率与大豆的最大吸水率之间有密切的关系。     

稻草纤维低聚糖的超声波辅助水解及分级凝析分析

研究了制备稻草纤维低聚糖的超声波辅助水解及分级凝析方法,结果表明:超声波辐照强度的变化将对稻草纤维结晶区结构的变化、糖苷键的断裂及分子聚合度的改变产生显著性影响。当稻草纤维5.00 g,超声波功率180 W,反应时间60 min,沉降时间120 min时,稻草水解的主要产物为纤维三糖和纤维四糖,低聚糖总产率为42.9%,是未施加超声波处理的酸水解对照组的最高产率的3.46倍,反应和凝析时间也分别缩短了1/3和1/2。分级凝析技术可作为一种从低聚糖产物所在的聚合度分布区间中获取所需区段产品的方法。     

豆腐皮废甜浆中大豆低聚糖的树脂脱色研究

从豆腐皮废甜浆中提取的大豆低聚糖粗溶液具有较深的颜色,不符合大豆低聚糖的产品标准。采用静态吸附法和解吸法研究10种树脂对大豆低聚糖溶液中色素的吸附性能及其解吸特性,筛选出脱色效果较好的树脂;同时确定树脂的吸附动力学曲线和吸附等温线模型。结果表明：在所选树脂中大孔吸附树脂DM-130和AB-8对于色素的去除效果最好,脱色率达到70%以上;树脂再生容易,体积分数50%的乙醇溶液几乎可以将色素全部洗脱;树脂对色素的吸附是单分子层吸附,吸附模型符合Langmuir吸附等温线;树脂DM-130和AB-8对大豆低聚糖的吸附率较小,具有实际的应用价值。     

溶液pH对不同超滤膜超滤大豆黄浆水的影响

实验研究溶液pH值对不同超滤膜超滤大豆黄浆水的影响。结果表明,当溶液pH值偏离大豆蛋白等电点时,渗透通量增大,膜衰减系数减小,蛋白质截留率变化不大,总糖透过率略有上升,PES-10膜的适宜pH为11,PS-10膜的适宜pH为6.2。     

苯胺柱前衍生麦芽糊精的高效液相色谱-电喷雾质谱分析

研究苯胺柱前衍生寡糖混合物麦芽糊精的高效液相色谱-电喷雾质谱分析方法。优化色谱及质谱分析的条件,采用反相C18色谱柱(4.6mm×250mm,5μm);乙腈和乙酸铵溶液(pH4.5、10mmol/L)为流动相进行梯度洗脱;在239nm波长处检测,并采用高效液相色谱-电喷雾质谱联用技术对寡糖衍生物进行分析,建立苯胺衍生寡糖的高效液相色谱(HPLC)分离分析、电喷雾质谱(ESI-MS)及液相色谱-电喷雾质谱联用(LC-ESI-MS)组分分析方法。在液质联用条件下,麦芽糊精衍生物分离效果良好。该方法衍生化产物稳定,后处理简单,在食品体系寡糖混合物分离分析方面有潜在的应用前景。     

Purification and biochemical characterization of an alpha-glucosidase from Xanthophyllomyces dendrorhous

Xanthophyllomyces dendrorhous grown in different media shows amylolytic activity, consisting in an extracellular exo-acting enzyme able to hydrolysed alpha,1-4 glycosidic bonds from soluble starch, which also cleaves maltose and malto-oligosaccharides. The enzyme was purified, using basically a couple of chromatography process on DEAE-Sephacel. It is a glycoprotein with a molecular weight estimated to be 60.2 kDa based on its mobility in SDS-PAGE and 115 kDa based on gel filtration. N-linked carbohydrate accounts for 12% of the total mass. It exhibited optimum activity at pH 5.5 and 45 degrees C. Thermostability analysis indicated that it was stable to thermal treatment up to 50 degrees C; 50% of the activity was maintained after 3 h. The rate parameters measured for the hydrolysis of starch and various chain length malto-oligosaccharides shows high catalytic efficiency, calculated by the relationship V(cat)/K(m), for malto-oligosaccharides, such as maltotriose (873 mM(-1) min(-1)), or maltoheptose (698 mM(-1) min(-1)). The new enzyme hydrolysed soluble starch with nearly 3.5- and 1.4-fold lower efficiency than that for maltotriose and maltose, respectively. No activity was found on heterogeneous substrates, such as sucrose and aryl alpha-glucoside, or on isomalto-oligosaccharides. In accordance to substrate specificity profile, the new enzyme was classified as an alpha-glucosidase.     

膳食纤维的定义、分析方法和摄入现状

本文主要论述膳食纤维的定义、分析方法以及人群摄入情况.中国营养学会将膳食纤维定义为不易被消化酶消化的多糖类食物成分(主要来自于植物的细胞壁),包含纤维素、半纤维素、树脂、果胶及木质素等.这种定义和FAO/WHO对膳食纤维狭义上的定义基本一致.而欧盟将其定义为具有3个或以上单体链节的碳水化合物聚合物,在人体小肠中不能被消化或吸收,包括天然存在于消费食物中的可食用的碳水化合物,由食物原料经物理、酶或化学法获得的碳水化合物,对健康表现出有益的生理作用的人造碳水化合物聚合物.根据现有定义,适用的主要分析方法有非酶重量法、酶重量法、酶化学法等.这些方法都是借鉴于AOAC方法.     

Influence of Galactooligosaccharides and Modified Waxy Maize Starch on Some Attributes of Yogurt

Abstract: This study examined the influence of galactooligosaccharides (GOS) and modified waxy maize starch (MWMS) addition on the growth of starter cultures, and syneresis and firmness of low‐fat yogurt during storage for 28 d at 4 °C. The control yogurt (CY) was prepared without any prebiotics. Incorporation of 2.0% (w/v) GOS improved the growth of L. delbrueckii ssp. bulgaricus ATCC 11842 resulting in a shorter fermentation time. There was a significant (P < 0.05) increase in proteolysis in yogurt made with GOS (GOSY) as measured by absorbance value (0.728). Addition of GOS resulted in higher (P < 0.05) concentration of lactic and acetic acids in comparison with that of MWMSY and the CY up to day 14, thereafter, the product showed a decrease in lactic acid content in all 3 batches until the end of storage. The level of syneresis was the lowest (2.14%) in MWMSY as compared with that of GOSY (2.35%) and CY (2.53%). There was no statistically significant (P > 0.05) difference in the firmness among the 3 types of yogurt.