寡聚酸合锌(Ⅱ)的合成及对烟草病毒病的防治

在水-乙醇介质中,用寡聚酸钾与硫酸锌反应合成的寡聚酸合锌(Ⅱ)配合物,采用正交实验考察了V水∶V乙醇,反应温度,反应时间对螯合反应的影响,最优反应条件为:V水∶乙醇=1∶1;温度60℃;时间5h.通过红外光谱、紫外光谱和差热-热重分析测试手段对配合物进行了表征.红外光谱和紫外光谱均显示,Zn2+与寡聚酸配位.寡聚酸合锌(Ⅱ)配合物中金属配位方式为单齿和双齿配位.热分析表明,配合物稳定性较强.应用寡聚酸合锌(Ⅱ)防治烟草病毒病,试验结果表明寡聚酸合锌(Ⅱ)具有较强的防治烟草病毒病的作用.寡聚酸合锌(Ⅱ)作为新型的抗病毒制剂具有广阔的开发前景.     

Polymer-supported oligosaccharide synthesis using ultrafiltration methodology

Polymer-supported oligosaccharide synthesis was carried out using an ultrafiltration technique in which the synthesized polymer-bound oligosaccharides were separated from the other reagents by ultrafiltration though membranes with specifically sized pores.     

Evaluation of Sample Preparation Strategies for Human Milk and Plasma Proteomics

Sample preparation is the most critical step in proteomics as it directly affects the subset of proteins and peptides that can be reliably identified and quantified. Although a variety of efficient and reproducible sample preparation strategies have been developed, their applicability and efficacy depends much on the biological sample. Here, three approaches were evaluated for the human milk and plasma proteomes. Protein extracts were digested either in an ultrafiltration unit (filter-aided sample preparation, FASP) or in-solution (ISD). ISD samples were desalted by solid-phase extraction prior to nRPC-ESI-MS/MS. Additionally, milk and plasma samples were directly digested by FASP without prior protein precipitation. Each strategy provided inherent advantages and disadvantages for milk and plasma. FASP appeared to be the most time efficient procedure with a low miscleavage rate when used for a biological sample aliquot, but quantitation was less reproducible. A prior protein precipitation step improved the quantitation by FASP due to significantly higher peak areas for plasma and a much better reproducibility for milk. Moreover, the miscleavage rate for milk, the identification rate for plasma, and the carbamidomethylation efficiency were improved. In contrast, ISD of both milk and plasma resulted in higher miscleavage rates and is therefore less suitable for targeted proteomics.     

小分子醇对PVDF／PFSA共混膜凝胶动力学、膜结构及膜性能的影响

以小分子醇为添加剂,研究了小分子醇对聚偏氟乙烯(PVDF)/全氟磺酸(PFSA)共混超滤膜凝胶动力学、结构与渗透性能的影响.结果表明:在PVDF/PFSA铸膜液中添加乙醇时,其凝胶速率随乙醇浓度的增加而加快,超滤膜通量随乙醇浓度的增加而增大;而当添加相同浓度的4种小分子醇时,初始凝胶速率差别不大,20 s后添加乙醇的铸膜液的凝胶速率最大;添加小分子醇后超滤膜的水通量大小顺序为:异丙醇<甲醇<乙醇<正丁醇.SEM照片显示在铸膜液中添加5%乙醇所制备的共混超滤膜具有较为圆整的内腔结构与均匀的孔结构.     

High-performance liquid chromatographic procedure for routine residue monitoring of seven sulfonamides in milk

A simplified method for routine monitoring of 7 residual sulfonamides (SAs) (sulfadiazine (SDZ), sulfamerazine (SMR), sulfadimidine (SDD), sulfamonomethoxine (SMM), sulfamethoxazole (SMX), sulfadimethoxine (SDM), and sulfaquinoxaline (SQ)) in milk using high-performance liquid chromatography (HPLC) with a photodiode array detector is described. The spiked and blank samples were cleaned up by using an Ultrafree-MC/PL centrifugal ultrafiltration unit. For determination/identification, a Mightysil RP-4 GP column and a mobile phase of 25% (v/v) ethanol in water with a photodiode array detector were used. Average recoveries from milk samples spiked with 0.05, 0.1, 0.2, and 0.5 microg mL(-1) of each drug were >82%. The inter- and intra-assay variabilities were 2.0-3.1%. The practical detection limits for 7 SAs were 0.005-0.02 microg mL(-1). The total time and amount of solvent required for the analysis of one sample were <40 min and <6 mL of ethanol, respectively. No toxic solvents were used.     

新的滇桂艾纳香寡糖BROS结构分析

以滇桂艾纳香枝叶为原料,经陶瓷膜、有机膜分离,醇沉、Sevag法除蛋白,DEAE-纤维素柱层析和SephadexG- 10,SephadexG-50凝胶柱色谱纯化得到的BROS;经HPGPC检测分析表明,BROS为均一寡糖,MALDI-TOF-MS测定分子量为1314.用IR,HPLC,甲基化分析,GC-MS,NMR (1H NMR,13C NMR,1H)HCOSY,HMQC和HMBC)等方法对BROS结构进行表征,结果表明,该寡糖由1个葡萄糖(α-D-Glcp)和7个果糖(β-D-Fru组成,残基间以→2)Fruf-(1→链接,分子末端链接为a-Glcp-(1→,→2)-β-D-Fruf推出BROS的结构式为:β-D-Fruf1-(2→1)-β-D-Fruf2-(2→1)-β-D-Fruf3-(2→ 1)-β-D-Fruf4-(2→1)-β -D-Fruf5-(2→1)-β-D-Fruf6-(2→ 1)-β-D-Fruf7-(2→ 1)-a-D-Glcp.     

牛蒡寡糖的分离纯化及结构研究

以菊科植物牛蒡(ArctiumlappaL.)的等外根为材料,经热水浸提、木瓜蛋白酶-Sevag法脱蛋白、乙醇沉淀和SephadexG-50凝胶柱层析分离纯化,得到水溶性的牛蒡寡糖(BOS₂).采用化学分析方法研究了BOS₂的理化性质,并通过TLC,GC-MS,HP-GPC,UV,IR,¹HNMR及¹³CNMR等对BOS₂的纯度、结构和组成进行表征.结果表明,BOS₂由果糖和葡萄糖组成,摩尔比约为12∶1,纯度较高,为均一性组分;由12个呋喃型的果糖以β(2→1)糖苷键相连,1个吡喃型的葡萄糖以α(1→2)糖苷键连接在果糖末端的线性直链结构,是一种菊糖构型的低聚果糖.     

Effect of temperature on the salt balance of milk studied by capillary ion electrophoresis

Many inorganic species, such as calcium, phosphate and magnesium, are in equilibrium between the liquid and colloidal phases of milk and hence are of importance with respect to the coagulation properties of milk. Capillary ion electrophoresis makes possible the determination of anions and cations in less than 6 min. The soluble phase of milk was obtained by ultrafiltration and samples had to be diluted 250-fold before analysis. Cold storage increased soluble calcium and phosphate concentrations, and warm-up of the milk restored the initial ionic equilibria. More drastic heat treatments (80–90°C) caused precipitation of tricalcium phosphate and calcium citrate.     

High performance polyethersulfone UF membrane for manufacturing spiral wound module: preparation,morphology, performance,and chemical cleaning

Large sheet asymmetric polyethersulfone (PES) ultrafiltration membranes were prepared via phase inversion process in a continuous conveyor system with addition of PVP to the casting solution. Dimethylacetamide (DMAc) and mixture of water and isopropyl alcohol (70/30 v%) were used as solvent and non‐solvent respectively. The prepared membrane was 0.96 m wide and 3 m long. The pieces of the membrane were selected randomly for characterization in terms of performance using cross flow filtration for milk concentration, image analysis, scanning electron microscopy (SEM), and cleaning procedures. It was found that the prepared membrane has high porosity and high water flux during milk filtration. In addition, cleaning experiments indicated that NaOH/HCl/NaOH sequence is an effective procedure for cleaning the fouled membrane during milk concentration. Copyright © 2007 John Wiley & Sons, Ltd.     

Dynamic modelling of milk ultrafiltration by artificial neural network

Artificial neural networks (ANNs) have been used to dynamically model crossflow ultrafiltration of milk. It aims to predict permeate flux, total hydraulic resistance and the milk components rejection (protein, fat, lactose, ash and total solids) as a function of transmembrane pressure and processing time. Dynamic modelling of ultrafiltration performance of colloidal systems (such as milk) is very important for designing of a new process and better understanding of the present process. Such processes show complex non-linear behaviour due to unknown interactions between compounds of a colloidal system, thus the theoretical approaches were not being able to successfully model the process. In this work, emphasis has been focused on intelligent selection of training data, using few training data points and small network. Also it has been tried to test the ANN ability to predict new data that may not be originally available. Two neural network models were constructed to predict the flux/total resistance and rejection during ultrafiltration of milk. The results showed that there is an excellent agreement between the validation data (not used in training) and modelled data, with average errors less than 1%. Also the trained networks are able to accurately capture the non-linear dynamics of milk ultrafiltration even for a new condition that has not been used in the training process.     

Direct determination of copper and zinc in cow milk, human milk and infant formula samples using electrothermal atomization atomic absorption spectrometry

Infant formula and powdered milk samples were suspended in a medium containing 20% ethanol, 0.65% nitric acid, 6% hydrogen peroxide and 0.1% ammonium dihydrogenphosphate and directly introduced in the electrothermal atomizer. Liquid milk samples were diluted with this suspension solution. The build-up of carbonaceous residues inside the atomizer was avoided by using a combination of hydrogen peroxide and nitric acid. Fast programs were used to simplify the heating cycles. Calibration was carried out using aqueous standards and the detection limits for copper and zinc were found to be 70 and 15 pg, respectively. The metal contents of several milk samples obtained by direct introduction of the samples agree with those obtained by means of a conventional procedure based on the total dissolution of the samples. The reliability of the methods was also confirmed by analyzing three certified reference materials. The free and protein binding fractions were measured by ultrafiltration membrane permeability of the milk samples.     

Integrated Downstream Processing of Lactoperoxidase from Milk Whey Involving Aqueous Two-Phase Extraction and Ultrasound-Assisted Ultrafiltration

The present work involves the adoption of an integrated approach for the purification of lactoperoxidase from milk whey by coupling aqueous two-phase extraction (ATPE) with ultrasound-assisted ultrafiltration. The effect of system parameters of ATPE such as type of phase system, polyethylene glycol (PEG) molecular mass, system pH, tie line length and phase volume ratio was evaluated so as to obtain differential partitioning of contaminant proteins and lactoperoxidase in top and bottom phases, respectively. PEG 6000-potassium phosphate system was found to be suitable for the maximum activity recovery of lactoperoxidase 150.70% leading to 2.31-fold purity. Further, concentration and purification of enzyme was attempted using ultrafiltration. The activity recovery and purification factor achieved after ultrafiltration were 149.85% and 3.53-fold, respectively. To optimise productivity and cost-effectiveness of integrated process, influence of ultrasound for the enhancement of permeate flux during ultrafiltration was also investigated. Intermittent use of ultrasound along with stirring (2 min acoustic and 2 min stirring) resulted in increased permeate flux from 0.94 to 2.18 l/m² h in comparison to the ultrafiltration without ultrasound. The use of ultrasound during ultrafiltration resulted in increase in flux, but there was no significant change in activity recovery and purification factor. The integrated approach involving ATPE and ultrafiltration may prove to be a feasible method for the downstream processing of lactoperoxidase from milk whey.     

Molecular weight and monosaccharide composition of Astragalus polysaccharides

Two polysaccharides (APS-I and APS-II) were isolated from the water extract of Radix Astragali and purified through ethanol precipitation, deproteination and by ion-exchange and gel-filtration chromatography. Their molecular weight was determined using high performance liquid chromatography and gel permeation chromatography (HPLC-GPC) and their monosaccharide composition was analyzed by TLC and HPLC methods, using a refractive index detector (RID) and an NH(2) column. It was shown that APS-I consisted of arabinose and glucose and APS-II consisted of rhamnose, arabinose and glucose, in a molar ratio of 1:3.45 and 1:6.25:17.86, respectively. The molecular weights (Mw) of APS-I and APS-II were 1,699,100 Da and 1,197,600 Da, respectively.     

血清中葡萄糖的测量比对-ID-LC—MS／MS法

利用同位素稀释-液相色谱-质谱法-（ID-LC-MS／MS）准确测定血清中葡萄糖含量。以[13C6]葡萄糖为内标,用重量法准确地与血清混合,离心沉淀蛋白后在碱性条件下与1．苯基-3-甲基-5-吡唑酮反应,以ZORBAXRX-SIL色谱柱分离,以乙腈-水（体积此25：75）为流动相,使用电喷雾三重四极杆串联质谱多重反应监测模式（MRM）测定,同位素稀释的括号法进行定量。采用美国NIST的血清标准物质SRM965b进行了确证,并用该方法参加JCTLM关于血清中葡萄糖含量的国际比对,测量值与均值的相对偏差分别为1．1％（A样）．1．8％（B样）,结果在等效范围内。     

Conversion of syngas to higher alcohols over Cu-Fe-Zr catalysts induced by ethanol

Ethanol induced method was applied to prepare Cu-Fe-Zr catalysts for conversion of syngas to higher alcohols. The catalytic performance of the catalysts induced by ethanol was superior to that of the catalyst prepared by the conventional precipitation method. Among various procedures for ethanol induced method, it was found that incorporation of ethanol in the precipitation process was the better. After incorporation of ethanol, the crystal size of CuO decreased and the reduction of copper species became easier. The better activity of Cu-Fe-Zr catalysts prepared by ethanol induced procedures was probably caused by the higher dispersion of Cu species.     

样品制备方法对高效液相色谱-串联质谱分析人乳内源肽的影响

人乳内源肽是乳蛋白在乳腺中被降解形成的具有生理功能的肽,是人乳的重要组成部分,研究人乳内源肽对于婴儿健康具有重要的意义。高效液相色谱-串联质谱(LC-MS/MS)联用技术的应用,促使人乳内源肽的研究取得了突破性的进展。人乳中内源肽含量低、干扰组分多,样品制备方法是影响分析结果的关键步骤。为了研究样品制备方法对分析结果的影响,分别采用不变性超滤法(UF 1)、热变性超滤法(UF 2)、化学变性超滤法(UF 3)、三氯乙酸沉淀法(PCPN 1)、乙醇沉淀法(PCPN 2)、强疏水性碳介孔材料(highly ordered mesoporous carbon, OMC)富集法等6种方法从人乳中提取内源肽,利用LC-MS/MS研究样品制备方法对人乳内源肽分析结果的影响。结果表明,UF 1和UF 2法制备的样品中可鉴定到的肽段数目分别为1161±8条和1017±91条,两种方法制备的样品中肽序列的重合率大于70%, UF 1在所有方法中鉴定到的肽的数目最多。UF 3法制备的样品所能鉴定到的肽段数目最少,仅为366±18条。PCPN 1和PCPN 2两种沉淀法制备样品中的内源肽分别为779±69和876±55条,但内源肽差异较大,仅有约50%肽段序列重合。OMC法制备样品中肽的数目为549±151条,与其他方法相比,虽然鉴定的肽数量上没有优势,但该方法制备的样品中肽在等电点(pI)和亲水性平均系数(GRAVY)等性质上没有偏倚,说明该法可用于制备特定人乳内源肽。6种方法制备的样品中鉴定到来源于β-酪蛋白、免疫球蛋白受体、骨桥蛋白、α_S1-酪蛋白、κ-酪蛋白和胆盐激活脂肪酶的肽,并且源于以上蛋白质的肽段总数在该样品中均超过88%,说明6种方法制备的样品都可以满足鉴定一般人乳内源肽的需求。UF 2、UF 3和OMC法制备的样品中鉴定到源于乳铁蛋白的内源肽的数目分别为21、38和19条,内源肽在乳铁蛋白上的覆盖率分别为14%、16%和19%,而文献常用的PCPN 1法制备的样品则会丢失此类内源肽。综上,UF 2法制备的样品不仅肽段数量多、母体蛋白质种类丰富,还可鉴定到源于乳铁蛋白的肽,可作为人乳内源肽组学研究中的首选方法。     

In-line determination of metabolites and milk components with electrochemical biosensors

Electrochemical biosensors for lactate, pyruvate and β-hydroxybutyrate based on oxygen, hydrogen peroxide, and NADH sensors coupled with oxidase and dehydrogenase enzymes were developed and used in conjunction with an artificial pancreas in experiments with extracorporeal circulation. Such procedures allow the fate of these species involved in glucose metabolism to be clarified during insulin treatment of diabetic patients. Studies with a glucose oxidase electrode for in-line determination of glucose produced by hydrolysis of cellobiose in a bioreactor are reported; for the determination of glucose in the presence of high concentrations of cellobiose, the purity of glucose oxidase is important in obtaining linear calibration plots. Impurities like amylase, maltase, invertase, and galactose oxidase, which are usually present in commercial preparations of glucose oxidase, must be absent. Another application is the amperometric determination of lactose, lactate and glucose in milk samples by using a hydrogen peroxide sensor coupled with β-galactosidase, lactate oxidase and glucose oxidase. The procedures outlined are simple and the short response times enable milk to be monitored during processing.     

Use of membrane processing to concentrate TGF-β2 and IGF-I from bovine milk and whey

The aim of this study was to evaluate the potential of using membrane processing such as microfiltration and ultrafiltration to concentrate TGF-β2 and IGF-I from milk and whey. Cheese wheys were obtained from Cheddar and Mozzarella cheeses made from pasteurized or thermized milk. Microfiltered or unheated whey (MF-whey) obtained by microfiltration of raw skim milk was used as control. Important losses of TGF-β2 were observed during clarification of pasteurized cheese wheys by microfiltration using a 1.4 μm pore size membrane. The ratio of IGF-I/TGF-β2 decreased from >3500 to 17 upon concentration of cheese whey by ultrafiltration (UF) and diafiltration (DF). UF concentration of MF-whey showed an increased concentration of TGF-β2 by a 13× factor. Lymphocyte proliferations increased upon MF/UF concentration and reached 25.5% inhibition at a 100 μg/mL concentration for MF-WPI, whereas a maximum of 8.5% of lymphocyte proliferation's inhibition was observed for cheese-WPI. Our results suggest that that UF/DF concentration of MF-whey may be a suitable method to prepare whey protein isolates enriched in TGF-β2 and IGF-I.     

Determination of polydextrose as dietary fiber in foods

Polydextrose (Litesse) provides physiological effects consistent with dietary fiber. However, AOAC methods for measuring total dietary fiber (TDF) in foods include an ethanol precipitation step in which polydextrose and similar carbohydrates are discarded and therefore not quantitated. This study describes a method developed to quantitate polydextrose in foods. The new method includes water extraction, centrifugal ultrafiltration, multienzyme hydrolysis, and anion exchange chromatography with electrochemical detection. Six foods were prepared with 4 levels of polydextrose to test the ruggedness of the method. Internal validation demonstrated the ruggedness of the method with recoveries ranging from 83 to 104% with an average of 95% (n = 24) and relative standard deviation of recoveries ranging from 0.7 to 13% with an average of 3.3% (n = 24). The value is added to that obtained for dietary fiber content of foods using the AOAC methods, to determine the TDF content of the food.     

In vitro and in vivo antioxidant activity of a water-soluble polysaccharide from Dendrobium denneanum

The water-soluble crude polysaccharide (DDP) obtained from the aqueous extracts of the stem of Dendrobium denneanum through hot water extraction followed by ethanol precipitation, was found to have an average molecular weight (Mw) of about 484.7 kDa. Monosaccharide analysis revealed that DDP was composed of arabinose, xylose, mannose, glucose and galactose in a molar ratio of 1.00:2.66:8.92:34.20:10.16. The investigation of antioxidant activity both in vitro and in vivo showed that DDP is a potential antioxidant.