纤维低聚糖的分离纯化研究

纤维低聚糖的分离纯化是研究纤维低聚糖的生理功能和化学结构的关键技术之一。利用聚丙烯酰胺凝胶(Bio-GelP-2)柱分离纤维低聚糖,分析了凝胶柱长、洗脱速度和上样浓度对分离效果的影响。结果表明:过长的柱长不能提高分辨率,过大的洗脱速度和上样浓度使分辩率降低,分离度减小。用2.5cm×125cm凝胶柱在上样浓度0.65g/mL、上样体积4mL、洗脱速度6.88cm/h条件下有好的分离效果,满足制备性分离。     

黑小麦功能性低聚糖的分离与组成分析

研究黑小麦麸皮功能性低聚糖的分离制备方法,并对其组成进行分析。采用木聚糖酶酶解黑小麦麸皮不溶性膳食纤维,所得酶解液经活性炭柱层析进行分离,并利用液相色谱和离子色谱对分离组分的单糖组成、低聚糖组成以及阿魏酰基团进行检测。结果表明,活性炭柱层析的水洗组分(WO)、不同浓度醇洗组分(EO)的低聚糖均主要由阿拉伯糖和木糖组成,为阿拉伯低聚木糖。其中,WO含有结合态阿魏酸,为阿魏酰低聚糖。WO的低聚糖聚合度较高,为DP 4~7;醇洗组分EO的低聚糖聚合度较低,为DP 2~4。     

凝胶过滤层析分离纤维低聚糖

纤维低聚糖具有重要的生理功能,是一种功能性食品基料。低聚糖的分离方法有很多种,柱层析是分离低聚糖的重要方法之一。利用聚丙烯酰胺凝胶柱(Bio-Gel P-2)层析能将水溶性纤维低聚糖混合物很好的分离开来,二次分离可得到白色的纤维二糖~五糖的单一组分的。在水-乙醇溶液中,纤维五糖和四糖析出的白色固体粘附在瓶壁上,析出的纤维三糖和纤维二糖成白色粉末状。     

酶法制备葛根纤维低聚糖

以葛根膳食纤维为原料,采用酶法制备功能性纤维低聚糖,并采用高效阴离子交换色谱法测定所制备样品的糖分组成。研究酶制剂、酶解时间和酶用量对纤维低聚糖组分及含量的影响。结果表明：选择β-葡聚糖酶制备纤维低聚糖优于纤维素酶,酶解产物主要成分为葡萄糖、纤维二糖和纤维三糖。β-葡聚糖酶法制备纤维低聚糖,酶解时间2h、酶用量3U/g时所得酶解产物中纤维二糖和纤维三糖所占比例均较高,纤维低聚糖得率为11.8g/100g。     

酶解香蕉茎干中纤维素的研究进展

本文简单介绍了酶解香蕉茎干中纤维素的研究背景, 对酶解纤维素的研究状况作了综述, 对用纤维素酶把香蕉茎干降解成纤维低聚糖的可能性作了分析, 并对纤维低聚糖的分离方法进行了说明, 对纤维低聚糖的应用前景进行了展望。     

壳低聚糖铁(Ⅲ)配合物制备工艺的研究

实验用壳低聚糖与铁(Ⅲ)离子配合生成壳低聚糖铁(Ⅲ)配合物,研究pH值、底物浓度、时间对结合率的影响,并对其结构进行了初步研究.分析结果表明,壳低聚糖与铁(Ⅲ)能形成稳定的配合物,经紫外、红外光谱分析其配位的基团主要是-NH2基,铁离子的结合率高达22.36%.     

壳低聚糖铬(Ⅲ)配合物制备工艺的研究

用壳低聚糖与铬(Ⅲ)离子配合生成壳低聚糖铬(Ⅲ)配合物,研究pH值、温度、底物浓度、时间对结合率的影响,并对其结构进行初步研究.分析结果表明,壳低聚糖与铬(Ⅲ)能形成稳定的配合物,经红外、紫外光谱分析其配位的基团是-NH2基,铬离子的结合率高达25.04%.     

非专一性酶酶解壳聚糖的最佳工艺研究

以甲壳低聚糖(COS)平均相对分子质量为指标,研究纤维素酶以及以纤维素酶为主体与木瓜蛋白酶及果胶酶复配水解壳聚糖的最佳工艺条件。结果表明影响纤维酶水解壳聚糖因素的主次是:pH温度时间,最佳工艺条件为:pH=3.8,温度=60℃,时间=2.5h,可得到Mr=1467.3的甲壳低聚糖。为了适合工厂生产需要,在pH=4.4,温度=60℃,时间=2.5h条件下纤维素酶与木瓜蛋白酶及果胶酶复配,研究结果表明m(木瓜蛋白酶):m(纤维酶)=1:1时,甲壳低聚糖平均相对分子质量为1000.1,m(果胶酶):m(纤维素酶)=1/3:1时,甲壳低聚糖平均相对分子质量达1134.4。     

纤维素酶水解纤维低聚糖的研究

对纤维素酶催化水解纤维三糖、纤维四糖和纤维五糖的规律进行研究。结果表明：相对水解率随低聚糖聚合度增大而降低;中间产物低聚糖和底物低聚糖竞争性与酶作用,产物中低聚合度低聚糖优先被酶催化水解;过大的纤维素酶用量并不能显著增大水解率;相对水解率均随初始低聚糖浓度增大而减小;pH5.0 时,纤维素酶最适温度为55℃。     

有机酸催化水解纤维低聚糖的研究

有机酸催化水解纤维低聚糖的能力强弱顺序为:草酸>顺丁烯二酸>丙二酸>乙酸>甲酸>丁二酸,丁二酸不能催化水解纤维低聚糖。二元羧酸水解纤维低聚糖时的能力与其水溶液酸性强弱有关,酸性越强,催化水解能力越大,低聚糖的水解率高。有机酸水解纤维低聚糖是分步进行的,先生成葡萄糖和低一级的低聚糖,低一级的低聚糖再水解生成葡萄糖和更低一级的低聚糖。在初始低聚糖浓度为1.5 mg/m L、水解时间9 h和水解温度95℃的条件下,0.05 mmol/m L草酸分别催化水解纤维三糖、纤维四糖和纤维五糖后产物葡萄糖浓度分别为0.51、0.53和0.13 mg/m L。     

Basic subsite theory assumptions may not be applicable to hydrolysis of cellooligosaccharides by almond beta-glucosidase

Steady-state kinetic parameters for the hydrolysis of cellooligosaccharides by almond beta-glucosidase were evaluated at pH 5.0 and 25 degrees C in relation to the subsite theory (K. Hiromi, Biochem. Biophys. Res. Commun., 40, 1-6, 1970). The value of k0/Km decreased monotonously with increasing degree of polymerization (DP) of the substrates (DP = 2-6). Also, the Km and k0 values for cellotriose were smaller than those for cellobiose. These DP dependencies differ from those of most amylases and glucosidases studied so far, to which the subsite theory has been successfully applied. The subsite parameters could not be consistently obtained, which suggests that one or both of the two basic assumptions of the subsite theory might not be applicable to the hydrolysis of cellooligosaccharides by the enzyme. That is, the intrinsic rate of the hydrolysis may depend on the DP and/or there may be interaction between subsites for binding the glucose residues of a substrate.     

Enzymatic production of a soluble-fibre hydrolyzate from carrot pomace and its sugar composition

This study was conducted to determine the sugar composition of soluble dietary fibre from carrot pomace, a by-product from the carrot juice processing industry. Carrot pomace was treated with a mixture of 1% NaOH and 2% acetic acid, and the pretreated sample was hydrolyzed by edible snails crude enzyme. The supernatant portion was then treated with 85% ethanol and separated into alcohol-soluble dietary fibre (ASDF) and alcohol-insoluble dietary fibre (AIDF). AIDF increased from an initial value of 3.3 g/100 g to 41.7 g/100 g carrot pomace after 96 h of reaction. The AIDF contained rhamnose, arabinose, mannose, galactose, glucose and a small amount of xylose. Monosaccharides (glucose, fructose, galactose, arabinose), cellooligosaccharides (cellopentaose, cellotetraose, cellotriose, cellobiose), and galactooligosaccharides (galactotetraose, galactotriose) were detected in the ASDF.     

Basic subsite theory assumptions may not be applicable to hydrolysis of cellooligosaccharides by almond β-glucosidase

Steady-state kinetic parameters for the hydrolysis of cellooligosaccharides by almond β-glucosidase were evaluated at pH 5.0 and 25°C in relation to the subsite theory (K. Hiromi, Biochem. Biophys. Res. Commun., 40, 1–6, 1970). The value of k₀/K_m decreased monotonously with increasing degree of polymerization (DP) of the substrates (DP = 2–6). Also, the K_m and k₀ values for cellotriose were smaller than those for cellobiose. These DP dependencies differ from those of most amylases and glucosidases studied so far, to which the subsite theory has been successfully applied. The subsite parameters could not be consistently obtained, which suggests that one or both of the two basic assumptions of the subsite theory might not be applicable to the hydrolysis of cellooligosaccharides by the enzyme. That is, the intrinsic rate of the hydrolysis may depend on the DP and/or there may be interaction between subsites for binding the glucose residues of a substrate.     

纤维低聚糖分离纯化研究进展

纤维素水解可得纤维低聚糖,纤维低聚糖在水中有一定溶解度,在有机溶剂中微溶或不溶;纤维低聚糖是功能性低聚糖,可促进矿物质吸收、为双岐杆菌增殖因子等.该文综述纤维低聚糖分离纯化方法,包括柱层析法、毛细管电泳分离法和膜分离法等研究进展.     

Characterization and molecular cloning of cellobiose dehydrogenase from the brown-rot fungus Coniophora puteana

Cellobiose dehydrogenase (CDH) was purified from the brown-rot fungus Coniophora puteana grown in culture containing crystalline cellulose as a carbon source. The purified enzyme gave a single band at 115 kDa on SDS-PAGE and showed a typical flavocytochrome absorption spectrum. The enzyme oxidized both cellobiose and cellooligosaccharides, but not their monomer, glucose, suggesting typical kinetic features of CDH. A cDNA encoding CDH was cloned by RT-PCR using primers designed from the consensus sequences of known CDHs from white-rot fungi. The cDNA consists of 2448 bp, including an open reading frame encoding the 18 amino acids of the putative signal peptide and the 756 amino acids of the mature protein. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) data for tryptic fragments of the purified C. puteana CDH were consistent with partial amino acid sequences of the mature protein deduced from the cloned cDNA. Moreover, the sequences contained common characteristics of CDH, i.e., two possible residues for a heme ligand (Met 64 and His 160), a flavin-binding motif, and two glucose-methanol-choline oxidoreductase motifs. This is the first cloning of CDH from a brown-rot fungus, and the results suggest structural and kinetic similarity of C. puteana CDH to white-rot fungal CDHs.     

基于多源光谱分析技术的鱼油品牌判别方法研究

多源光谱分析技术被用于鱼油品牌快速无损鉴别。采用可见光谱分析技术、短波近红外光谱分析技术、长波近红外光谱分析技术、中红外光谱分析技术和核磁共振光谱分析技术采集了7种不同品牌的鱼油的光谱特征,并应用偏最小二乘判别分析法(partial least squares discrimination analysis,PLS-DA)和最小二乘支持向量机(least-squares support vector machine,LS-SVM)建立判别模型并比较判别结果。基于长波近红外光谱的PLS-DA模型和LS-SVM模型取得了最高识别正确率,建模集和预测集识别正确率均达到100%。采用中红外光谱和核磁共振谱分别建立的LS-SVM模型,也可以获得100%的判别正确率。而可见光谱和短波近红外光谱则判别准确率较差。且LS-SVM算法较PLS-DA更加适合用于建立光谱数据和鱼油品牌之间的判别模型。研究结果表面长波近红外光谱技术能够有效判别不同鱼油的品牌,为将来鱼油品质鉴定便携式仪器的开发提供了技术支持和理论依据。     

表面分析技术在制浆造纸研究中的应用

主要介绍了扫描电境(SEM)、透射电境(TEM)、原子力显微镜(AFM)、化学分析电子能谱(ESCA)、次级离子质谱(SIMS)、接触角(Contact Angle)、红外反射-吸收光谱(RAS)等现代表面分析技术及这些技术在制浆造纸研究中的应用.     

椰子粉中蔗糖和葡萄糖添加量的快速检测

以椰子原粉为原料,分别添加蔗糖和葡萄糖形成一系列含糖量梯度(2.5%~80%)的椰子粉样品。分别运用红外光谱和近红外光谱技术,利用偏最小二乘法(PLS)建立椰子粉中添加蔗糖和葡萄糖含量的模型,并进行校正、交叉验证和预测。结果显示:蔗糖的红外和近红外模型的校正、交叉验证、预测的相关系数R_C2、R_CV2、R_P2分别为0.8752、0.8501、0.8401和0.9888、0.9868、0.9856。葡萄糖的红外和近红外模型的校正、交叉验证、预测的相关系数R_C2、R_CV2、R_P2分别为0.8708、0.8500、0.8708和0.9569、0.9503、0.9572。结果表明:利用红外光谱数据和近红外光谱数据建立的椰子粉蔗糖和葡萄糖含量的模型良好,预测值与真实值接近。说明利用红外光谱技术和近红外光谱技术快速检测椰子粉中添加蔗糖和葡萄糖含量的方法是可行的,且相比之下,利用近红外光谱数据建立的模型更优良,预测更准确。