茉莉花香气释放酶的研究

茉莉花开放过程中 ,以PNPG为底物的 β_葡萄糖苷酶活性没有明显变化 ,同样丙酮粉中参与键合态芳樟醇释放的有关酶活性变化也不显著 ,但与键合态苯甲醇释放有关的酶活性却在离体后 6小时 ( 2 3∶0 0 )有一明显活性高峰 ,这一变化与游离态的苯甲醇变化规律相吻合 ;苯丙氨酸解氨酶在花初开时 ( 2 0∶0 0 )活性有所提高 ;非特异性酯酶同工酶谱带显示酯酶与香气释放有关 ;乙醇脱氢酶活性始终高于甲醇脱氢酶 ,而两种酶活性变化不大 ,前者在花前 ( 17∶0 0 )和花盛开时 ( 2∶0 0 )略有提     

外源酶提高铁观音杀青叶香气的工艺研究

为了提高铁观音杀青叶烟用香料中香气物质的得率,采用生物酶对原料进行酶解增香后再提取.采用顶空固相微萃取(HS-SPME)结合气相色谱-质谱联用(GC-MS)技术分析挥发性香气成分含量并进行感官评定.结果表明,先加入柠檬酸酸解再加入复合酶(纤维素酶0.03％、果胶酶0.03％和β-葡萄糖苷酶0.03％)酶解后,芳樟醇、香...     

β—葡萄糖苷酶固定化及其性质的研究

β-葡萄糖苷酶(EC3,2,1,21),又称β-D-葡萄糖苷葡萄糖水解酶,它能够水解结合于末端非还原性的β-D-葡萄糖键,同时释放出β-D-葡萄糖和相应的配基.在饮料工业中,特别是能够水解释放茶叶饮料中糖苷类香气成分(芳樟醇、香叶醇等),有着重要的应用价值.β-葡萄糖苷酶市场价格昂贵,且使用寿命和储存期短,因而在实际应用过程中使用受到限制,笔者选用壳聚糖作为β-葡萄糖苷酶的固定化载体,对固定化酶性质进行研究.     

茶叶香气释放机理研究——龙井茶炒制过程中β—葡萄糖苷酶和醇系香气的 …

选用水古、龙井４３、鸠坑三个品种的鲜叶,经摊放,杀青制成龙井茶。用气相色谱（ＧＣ）分析加工过程中游离香气和醇系香气前驱体变化。同时用比色法检测相应的β－葡萄糖苷酶的活性。结果表明,三个品种摊放叶酶活性均增加了４５％以上,醇系香气前驱体放量与酶活性趋势一致,用外源β－葡萄糖苷酶酶解鲜叶,摊放叶,测得香叶醇,芳樟醇,橙花醇等组份大量释放,说明该酶与萜烯香气前驱体有密切关系。     

武夷岩茶加工过程β-葡萄糖苷酶对香气形成的影响

通过分析武夷岩茶水仙和肉桂加工过程中β-葡萄糖苷酶活性以及香气成分,探讨β-葡萄糖苷酶对水仙和肉桂加工过程香气形成影响的差异性。结果表明,水仙香气含量和β-葡萄糖苷酶活性低于肉桂,但加工过程香气和β-葡萄糖苷酶活性变化率高于肉桂:水仙β-葡萄糖苷酶活性与香气、橙花叔醇、香叶醇均呈高度指数负相关,相关系数分别为0.931、0.973、0.999,与芳樟醇、雪松醇分别呈高度、较高指数正相关,相关系数分别为0.947、0.872:肉桂β-葡萄糖苷酶活性与香气、柽花叔醇、香叶醇、芳樟醇氧化物I呈较高指数负相关,相关系数分别为0.897、0.888、0.869、0.882。     

白茶加工过程中糖苷类香气成分的代谢变化

为探明白茶加工过程中糖苷类香气成分的代谢变化,本试验采用顶空固相微萃取/气相色谱-质谱联用法测定了糖苷类香气成分的含量;通过转录组测序分析了β-樱草糖苷酶及28条β-葡萄糖苷酶基因表达量,并进行qRT-PCR验证;采用对硝基苯酚显色法检测β-葡萄糖苷酶活性.结果表明芳樟醇、香叶醇、苯乙醇、苯甲醛、水杨酸甲酯在白茶加工过程中显著增加.在茶鲜叶萎凋减重≤20％阶段,β-樱草糖苷酶基因表达量降低,随后维持稳定;11条β-葡萄糖苷酶基因呈持续下调表达趋势,3条β-葡萄糖苷酶基因呈现上调表达趋势.在茶鲜叶萎凋减重≤30％阶段,β-葡萄糖苷酶活性提高,随后无明显变化.因此,根据糖苷类香气成分的形成途径推测樱草糖苷酶解作用对这些香气形成贡献较小.而CsGH1BG6和CsGH1BG21的表达对香叶醇和芳樟醇的积累略有贡献.     

茶叶香气释放机理研究──龙井茶炒制过程中β-葡萄糖苷酶和醇系香气的关系

选用水古、龙井43、鸠坑三个品种的鲜叶,经排放、杀有制成龙井茶。用气相色谱（GC）分析加工过程中游离香气和酸系香气前驱体变化,同时用比色法检测相应的β-葡萄糖苷酶的活性。结果表明,三个品种排放叶酶活性均增加了45％以上,醇系香气前驱体释放量与酶活性趋势一致。用外源β-葡萄糖苦酶酶解鲜叶、排放叶,测得香叶酸、芳樟醇、楼花醇等组份大量释放,说明该酶与萜烯类香气前驱体有密切关系。     

白兰花挥发性成分的GC-MS分析

以乙酸乙酯为提取溶剂,对阴干、冷冻白兰花样品及白兰花酊剂样品进行了超声提取,并采用超临界CO2(SFE)提取了白兰花挥发油,用气相色谱-质联联用法(GC-MS)共鉴定出59种化学成分,4种样品鉴定出化合物各占总挥发性成分的98.87%、99.72%、92.77%和96.21%,其中含量较高的物质有:芳樟醇(7.50%、17.61%、67.51%、70.42%)、苯乙醇(0.84%、1.36%、2.57%、2.61%)、丙酸乙酯(38.21%、6.36%、未检出、0.27%)、甲苯(34.52%、66.88%、未检出、未检出)等,并且白兰花特征性芳香成分芳樟醇在酊剂提取物和超临界CO2提取物中所占比例较高。     

抗黄曲霉毒素单克隆抗体F(ab')2片段的制备与活性

为剧毒靶标(黄曲霉毒素)绿色分析提供高效抗体,在已有抗黄曲霉毒素杂交瘤细胞株1Cll的基础上,通过小鼠腹水法制备单克隆抗体,经胃蛋白酶酶解,制备F(ab')2片段,发现在优化条件37C、pH4.1柠檬酸缓冲液中酶解4.5h,可高效制备F(ab')2片段.通过酶联免疫吸附法(ELISA)比较了抗体片段与原始抗体的识别活性,发现F(ab')2片段效价达到1∶320000,是原抗体效价的1.5倍;灵敏度(IC50)为8.7pg/mL,保持了原抗体的抗原结合能力.     

CXJZ95-198菌株果胶酶活力检测方法研究

本文采用DNS法,对影响CXJZ95-198菌株果胶酶活力测定的酶解反应条件进行了比较系统的研究。结果表明,酶解反应条件对酶活力测定值的影响明显,其中,温度、缓冲液种类、底物种类及其浓度对测定结果影响较大,缓冲液pH及DTT浓度对测定结果也有一定影响。测定该菌株果胶酶活力适宜的酶解反应条件为:温度50℃,底物桔子果胶S(igm a),底物浓度0.2%,缓冲液1/15m ol.L-1KH 2PO4-Na2H PO4(pH 5.2),DTT浓度为1.0m m ol.L-1。     

Purification and characterization of alcohol dehydrogenase from Gluconobacter suboxydans

Purification and characterization of alcohol dehydrogenase (ADH) from Gluconobacter suboxydans was done in order to biotechnological and industrial application. Solubilization of enzyme from bacterial membrane fraction by Triton X-100 and subsequent fractionation on DEAE-Sephadex A-50 and Hydroxyapatite was successful in enzyme purification. Enzyme assay reaction mixture contained potassium ferricyanide 0.1 M, McIlvaine buffer 0.1 M (pH 5.5), Triton X-100 10%, ethanol 1 M and enzyme solution. The purified ADH Optimum pH activity was 5.5. The enzyme was in maximum stability in pH 5.8. The substrate specificity of the enzyme was determined using the same enzyme assay method as described above, except that various substrates (100 mM) were used instead of ethanol. The relative activity of the ADH for ethanol was higher than the others. The effects of metal ions and inhibitors on the activity of the enzyme were examined by measuring the activity using the same assay method as described above. Activity of purified enzyme was increased in the presence of Ca(+2) and was decreased in presence the of ethylenediamine tetra acetic acid (EDTA). Because the proper structure and function of the enzyme is related to structural Ca(+2) and EDTA can chelate Ca(+2). An apparent Michaelis constant for ethanol were examined to be 1.7 x 10(-3) M for ethanol as substrate.     

Optimization of process parameters influencing the submerged fermentation of extracellular lipases from Pseudomonas aeruginosa, candida albicans and Aspergillus flavus

The present study was aimed at optimization, production and partial purification of lipases from Pseudomonas aeruginosa, Candida albicans and Aspergillus flavus. Various nutritional and physical parameters affecting lipase production such as carbon and nitrogen supplements, pH, temperature, agitation speed and incubation time were studied. Refined sunflower oil (1% v/v) and tryptone at a pH of 6.2 favored maximum lipase production in Pseudomonas at 30 degrees C and 150 rpm, when incubated for 5 days. In C. albicans refined sunflower oil (3% v/v) and peptone resulted in maximum lipase production at pH 5.2, 30 degrees C and 150 rpm, when incubated for 5 days. In A. flavus coconut oil (3% v/v) and peptone yielded maximum lipase at pH 6.2, 37 degrees C, 200 rpm after an incubation period of 5 days. The lipases were partially purified by ammonium sulphate precipitation and dialysis. In P. aeruginosa enzyme activity of the dialyzed fraction was found to be 400 U mL-' and for C. albicans 410 U mL(-1). The dialysed lipase fraction from A. flavus demonstrated an activity of 460 U mL(-1). The apparent molecular weights of the dialyzed lipases were determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The dialyzed lipase fraction obtained from P. aeruginosa revealed molecular weights of 47, 49 and 51 kDa, whereas, lipases from C. albicans and A. flavus demonstrated 3 bands (16.5, 27 and 51 kDa) and one band (47 kDa), respectively. These extracellular lipases may find wide industrial applications.     

茶树叶绿素酶提取、分离纯化与性质的初步研究

在优化茶树叶绿素酶提取及活性分析条件的基础上,对茶树叶绿素酶的分离纯化及其性质进行了研究,结果表明:加入与鲜叶等量PVP,用pH7.5的磷酸二氢钠-磷酸氢二钠缓冲液提取的叶绿素酶活性最高,叶绿素酶的活性分析最佳条件为在45℃条件下反应15min;经过分离纯化后,叶绿素酶的纯度提高了55.96倍,酶的得率为9.45%,SDS-PAGE结果显示有一条蛋白质的条带,酶的亚基分子量为37.2kD;对纯化后的叶绿素酶的性质研究表明,该酶最适pH为7.5,45℃时候反应活性最高,在4℃保存条件下,随着存放时间的延长,酶活性逐渐下降,保存一个月后叶绿素酶活性剩余45%,用2mmol/L和7mmol/L的金属离子(Ca2+、Mg2+、Zn2+、Fe3+)、EDTA处理,都对叶绿素酶活性有不同程度的促进作用。     

Antiviral Sulfoquinovosyldiacylglycerols (SQDGs) from the Brazilian Brown Seaweed Sargassum vulgare

Total lipids from the Brazilian brown seaweed Sargassum vulgare were extracted with chloroform/methanol 2:1 and 1:2 (v/v) at room temperature. After performing Folch partition of the crude lipid extract, the lipids recovered from the Folch lower layer were fractionated on a silica gel column eluted with chloroform, acetone and methanol. The fraction eluted with methanol, presented a strong orcinol-positive band characteristic of the presence of sulfatides when examined by TLC. This fraction was then purified by two successive silica gel column chromatography giving rise to fractions F4I86 and F4II90 that exhibited strong activity against herpes simplex virus type 1 and 2. The chemical structures present in both fractions were elucidated by ESI-MS and ¹H/¹³C NMR analysis HSQC fingerprints based on their tandem–MS behavior as sulfoquinovosildiacylglycerols (SQDGs). The main SQDG present in both fractions and responsible for the anti-herpes activity observed was identified as 1,2-di-O-palmitoyl-3-O-(6-sulfo-α-d-quinovopyranosyl)-glycerol.     

RP—HPLC法测定泽兰中木犀草素-7-0-β-D-葡萄糖苷的含量

目的建立反相高效液相色潜法测定泽兰中木犀草素-7-0-β-D-葡萄糖苷的含量。方法采用AlltimaTM—C18（250minx4．6mm,51．Lm）;以乙腈-0．2％磷酸水溶=20：80进行等度洗脱,流速为1．0ml／min,检测波长为350mm,柱温为35℃。结果木犀草素-7-0-β-D-葡萄糖苷的线性范围为0．412-10．30μg（r=0．9999）,平均回收率为100．25％。结论该方法结果准确、简便可行、重复性好,可为泽兰的质量控制提供依据。     

Squid Pen Chitin Chitooligomers as Food Colorants Absorbers

One of the most promising applications of chitosanase is the conversion of chitinous biowaste into bioactive chitooligomers (COS). TKU033 chitosanase was induced from squid pen powder (SPP)-containing Bacillus cereus TKU033 medium and purified by ammonium sulfate precipitation and column chromatography. The enzyme was relatively more thermostable in the presence of the substrate and had an activity of 93% at 50 °C in a pH 5 buffer solution for 60 min. Furthermore, the enzyme used for the COS preparation was also studied. The enzyme products revealed various mixtures of COS that with different degrees of polymerization (DP), ranging from three to nine. In the culture medium, the fermented SPP was recovered, and it displayed a better adsorption rate (up to 96%) for the disperse dyes than the water-soluble food colorants, Allura Red AC (R40) and Tartrazne (Y4). Fourier transform-infrared spectroscopic (FT-IR) analysis proved that the adsorption of the dyes onto fermented SPP was a physical adsorption. Results also showed that fermented SPP was a favorable adsorber and could be employed as low-cost alternative for dye removal in wastewater treatment.     

Oil separation from wet-milled corn germ dispersions by aqueous oil extraction and aqueous enzymatic oil extraction

The many recent dry-grind plants that convert corn to ethanol are a potential source of substantial amounts of corn oil, if an economical method of separating it can be developed. Oil separation from corn germ by aqueous extraction (AE) was studied. Batches of 5–20% germ in a buffer solution were preheated in a pressure cooker, ground in a blender or colloid mill, churned in an incubator/shaker and centrifuged to separate a free oil fraction. The highest oil yields were obtained when the germ mass fraction was between 0.1 and 0.16. Addition of an enzyme solution to the ground germ suspension prior to churning, aqueous enzymatic extraction (AEE) gave an oil yield twice as high as the AE yield, carried out using similar conditions. Both types of extraction produced the most oil after a 122 °C cook followed by churning at 160 rpm and 70 °C. Oil yield increased linearly with dispersion loading, from 0.5 up to 1.0 g/cm² based on beaker cross-section (0.09–0.12 germ mass fraction). Over a several month period the germ used for the extractions became more difficult to extract, despite storage at 4 °C.     

茶树新梢内源激素的HPLC分析及日变化

研究了茶树新梢内源赤霉酸（ＧＡ３）、吲哚乙酸（ＩＡＡ）、吲哚乙醛（ＩＡＡＤ）、脱落酸（ＡＢＡ）和玉米素（Ｚｅａｔｉｎ）等激素的ＨＰＬＣ分析方法。在ＯＤＳ（Ｃ１８）反相柱上，ＧＡ３、ＩＡＡ、ＩＡＡＤ和ＡＢＡ用甲醇—乙腈—ＫＨ２ＰＯ４缓冲液系统为流动相、Ｚｅａｔｉｎ用甲醇—乙腈—磷酸缓冲液系统为流动相得到满意的分离，它们与相邻峰间的峰高分离度均在０．６５以上。在紫外波长λＧＡ３＝２１０ｎｍ，λＩＡＡ、ＩＡＡＤ、ＡＢＡ＝２８０ｎｍ和λＺｅａｔｉｎ＝２５４ｎｍ、灵敏度０．００３ａｕｆｓ（ＧＡ３）和０．００１ａｕｆｓ（ＩＡＡ、ＩＡＡＤ、ＡＢＡ和Ｚｅａｔｉｎ）条件下，各种激素得到定量。ＧＡ３、ＩＡＡ、ＩＡＡＤ、ＡＢＡ和Ｚｅａｔｉｎ的平均标样添加回收率分别为７６．２４％，８９．６９％，８４．３３％，９０．９６％和８２．０９％。茶树新梢内源激素含量在一天内有明显的变化，其高峰值均出现在１３时左右。一天内以１０—１６时取样进行内源激素测定较适宜     

玉米叶片谷氨酸合酶(GOGAT)的纯化和特性研究

玉米叶片的谷氨酸合酶(GOGAT)经硫酸铵分级沉淀处理后,与粗酶液相比较被纯化了1.71倍。在缓冲溶液pH值为7、酶溶液体积为6.25 mL、反应时间为12 min的条件下,谷氨酸合酶(GOGAT)的活性最高,该酶对底物谷氨酰胺(L-GIn)、α-酮戊二酸(α-KG)和电子供体(NADH)专一,其最适浓度分别为55、60、0.3 mmol/L,Km值分别为4.13、7.78、0.001 4 μmol/L。     

Purification of wheat flour high-molecular-weight glutenin subunits by fast protein liquid chromatography

Fast protein liquid chromatography has been developed for purification of high-molecular-weight glutenin subunits HMW-GSs from wheat flour. Flour samples from four wheat cultivars with different HMW-GS alleles at Glu-A1, Glu-B1 and Glu-D1 loci were used to establish the method. The column material used was Resource™ Phe, and the optimal elution was with a gradient formed with buffer A [0.05 M Tris–HCl containing 4 M urea and 0.25 M (NH₄)₂SO₄, pH 8.0] and buffer B [0.05 M Tris–HCl containing 4 M urea (pH 8.0)] at a flow rate of 0.5 ml/min. A pure single 1Dx-, 1Bx- HMW-GS, and all the y-type HMW-GSs present in one genotype can be reliably separated in a single step.