香菇多糖脱蛋白工艺的研究

从香菇菌丝体中提取的香菇多糖经脱蛋白提纯后，其生物活性更高。对酶法、Sevag法、三氯乙酸-正丁醇法脱蛋白效果进行了比较研究，确定了最佳的脱蛋白工艺为酶法和三氯乙酸．正丁醇结合法，脱色4次，蛋白含量为1．97％，多糖损失率为4．58％。     

香菇多糖脱蛋白工艺的研究

从香菇菌丝体中提取的香菇多糖经脱蛋白提纯后，其生物活性更高。对酶法、Sevag法、三氯乙酸-正丁醇法脱蛋白效果进行了比较研究，确定了最佳的脱蛋白工艺为酶法和三氯乙酸．正丁醇结合法，脱色4次，蛋白含量为1．97％，多糖损失率为4．58％。     

仙人掌多糖提取过程中三种脱蛋白方法的比较研究

用水提取的仙人掌多糖常舍有蛋白质，实验以多糖损失率和脱蛋白率为衡量指标。选用了3种方法：Sevag法、三氯乙酸法和酶法对仙人掌多糖提取物进行脱蛋白处理。实验结果表明：酶法、三氯乙酸法和Sevag法的脱蛋白率分别为89．6％、56．2％和45．5％，多糖损失率分别为7．2％、9．5％和13．6％。经比较认为：酶提取法是替代常规方法的一种有效方法。     

仙人掌多糖提取过程中三种脱蛋白方法的比较研究

用水提取的仙人掌多糖常含有蛋白质,实验以多糖损失率和脱蛋白率为衡量指标,选用了3种方法: Sevag法、三氯乙酸法和酶法对仙人掌多糖提取物进行脱蛋白处理.实验结果表明:酶法、三氯乙酸法和Sevag 法的脱蛋白率分别为89.6%、56.2%和45.5%,多糖损失率分别为7.2%、9.5%和13.6%.经比较认为:酶提取法是替代常规方法的一种有效方法.     

茶籽多糖的提取及脱蛋白工艺研究

采用热水浸提法从油茶籽粕中提取茶籽多糖,通过正交试验确定了茶籽多糖的最佳提取条件,并对比了Sevage法、三氯乙酸法、聚酰胺法、酶法脱蛋白的效果。结果表明:茶籽多糖最佳提取条件为料液比1∶10、提取温度70℃、提取时间3 h,在最佳提取条件下茶籽多糖得率为30.31%;采用碱性蛋白酶酶法脱蛋白效果最佳,其蛋白质脱除率为74.38%,茶籽多糖保留率为75.40%。     

仙人掌多糖提取过程中三种脱蛋白方法的比较研究

用水提取的仙人掌多糖常含有蛋白质．实验以多耱损失率和脱蛋白率为衡量指标，选用了3种方法：Sevag法、三氯乙酸法和醉法时仙人掌多糖提取物进行脱蛋白处理.实验结果表明：酶法、三氯乙酸法和Sevag法的脱蛋白率分别为89.6％、56．2％和45．5％．多糖损失率分别为7．2％、9．5％和13．6％，经比较认为：酶提取法是替代常规方法的一种有效方法。     

仙人掌多糖的提取及其对自由基的清除作用

对仙人掌多糖提取工艺条件度其体外抗氧化性进行了研究。结果表明，仙人掌多糖最佳提取工艺为：提取温度85℃，提取时间2h，固液比1：20，提取次数4次，经过酶法脱蛋白，多糖得率可达5.95％。蛋白质脱除率达到92．5％。蛋白质仙人掌多糖提取液的清除自由基的作用较明显。     

啤酒酵母多糖脱蛋白方法的应用研究

以提取的粗酵母多糖为原料,采用Sevag法及Sevag法与酶法结合对其进行脱蛋白.结果表明,Sevag法脱蛋白3次,Sevag试剂中的氯仿:正丁醇=5:1,糖液:Sevag=5:1脱蛋白效果最好,此时蛋白质残留量为6.392mg/mL,多糖损失率为24.62%.Sevag法与酶法结合脱蛋白,蛋白质水解的最佳工艺条件为:水解温度60℃,pH7.0,样液:酶液=3:1,时间为2h,此时蛋白质残留量为6.86mg/mL,多糖损失率仅19.74%.     

大米浓缩蛋白脱酰胺研究(Ⅰ)酸法脱酰胺与酶法脱酰胺工艺比较与参数优化

通过测定大米浓缩蛋白的脱酰胺度与水解度，比较了酸法与酶法两种脱酰胺工艺对大米浓缩蛋白脱酰胺作用的优劣，并对酸法脱酰胺工艺的参数进行优化。实验表明酸法脱酰胺优于酶法脱酰胺。温度是影响大米浓缩蛋白脱酰胺作用最重要的因素，在本试验条件范围内，酸法脱酰胺度最高且水解度最低时的工艺条件组合为盐酸浓度0．2N，大米蛋白含量5％，反应时间4h，反应温度85℃。     

云南野生玛卡多糖脱蛋白工艺研究

研究玛卡多糖的脱蛋白条件,以多糖保留率与蛋白清除率为考察指标,比较NaCl法、CaCl2法、酶法、Sevage法、TCA法、Sevage-酶法、TCA-酶法、NaCl-酶法和CaCl2-酶法的玛卡多糖的除蛋白效果,以筛选玛卡多糖最佳脱蛋白方法。结果表明,玛卡多糖最适脱蛋白工艺为Sevage-酶法,条件为酶浓度4%,酶解温度55℃,酶解时间1 h,pH 6,Sevage法4次。该法蛋白质清除率56.13%,多糖保留率80.32%。该条件下脱蛋白作用好,操作便捷,可用于工业化生产使用。     

响应面法优化牛皮酶法脱毛工艺

研究旨在探求复合酶脱毛的最优工艺条件,并为牛皮的开发利用提供了一定的理论基础。本试验以牛皮酶法脱毛过程中加酶方式、酶活力配比、酶液浓度、酶解时间、酶解pH、酶解温度等为研究因素,在单因素实验基础上进行复合酶脱毛方法,结合响应面法对复合酶脱毛工艺进行优化。结果表明,碱性蛋白酶和中性蛋白酶采用先后加入的酶解方式,得到了碱性蛋白酶和中性蛋白酶的最适酶活力配比、酶解温度、酶液浓度、酶解时间、pH值,测得综合评分为0.756。响应面法分析结果表明,酶解温度和酶液浓度的交互作用对脱毛效果的影响显著,而其他因素交互作用不显著。     

介孔分子筛MCM-48固定化木瓜蛋白酶性质的研究

以介孔分子筛MCM48为载体、戊二醛作交联剂对木瓜蛋白酶进行了固定化。实验结果表明,与游离酶相比,固定化酶的热稳定性有了显著的提高,其半衰期达到了2500min以上,是游离酶(80min)的30倍以上。固定化酶的pH稳定性和储藏稳定性也有了明显改善。此外,固定化酶还具有很好的操作稳定性,经过12d的连续酶解,酶活力仍保持在初始酶活力的70%以上。     

逐级盐析结合双水相法纯化贯筋藤凝乳酶

为了高效制备贯筋藤凝乳酶,利用逐级盐析结合双水相萃取对贯筋藤凝乳酶进行纯化,研究成相物质、聚乙二醇(PEG)/盐最佳纯化配比及酶用量对酶凝乳纯化的影响,应用SDS-PAGE电泳技术检测贯筋藤凝乳酶的纯度。结果表明:当硫酸铵饱和度区间为20%~40%,贯筋藤粗酶比活力较高,为167.846 MCA/mg;当PEG相对分子质量为6000且质量分数为20.57%、盐相为硫酸铵且质量分数为14.74%,酶用量为1.0 mL时,贯筋藤凝乳酶活力提高1.87倍。电泳图显示贯筋藤凝乳酶纯度较高,分子量约为25 kDa。利用双水相法分离纯化可获得高纯度的贯筋藤凝乳酶,可为贯筋藤凝乳酶后续规模化生产及应用提供参考价值。     

Effects of an enzyme feed additive on extent of digestion and milk production of lactating dairy cows

A study was conducted using lactating Holstein cows with ruminal and duodenal cannulas in a 4 x 4 Latin square design to investigate fibrolytic enzyme supplementation on site and extent of nutrient digestion. The four diets consisted of 45% concentrate, 10% barley silage, and 45% cubed alfalfa hay (dry matter basis) and differed in enzyme supplementation: 1) control cubes, 2) cubes treated with 1 g of enzyme mixture/kg of cubes, 3) cubes treated with 2 g of enzyme mixture/kg of cubes, and 4) both concentrate and cubes treated with 1 g of enzyme mixture/kg of dry matter. The enzyme supplement contained primarily cellulase and xylanase activities. Digestion of organic matter and neutral detergent fiber in the total tract was higher for cows fed the high dosage of enzyme than for cows fed the control cubes. Ruminal digestibility of crude protein was higher, but that of organic matter and neutral detergent fiber was only numerically higher, for cows fed the high dosage of enzyme compared with that of cows fed the control cubes. Higher ruminal digestibility associated with the high dosage of enzyme resulted in more microbial protein synthesis. Milk production increased for cows fed the high dosage of enzyme compared with cows fed the control cubes and effects of the addition of enzyme on milk composition were minimal. The results demonstrated the benefits of using a fibrolytic enzyme additive to enhance feed digestion and milk production by dairy cows. The response to enzyme supplementation was affected more by amount of enzyme than by whether the enzyme was added to forage or concentrate.     

双醛氧化纤维素固定化β-半乳糖苷酶

以双醛氧化纤维素为载体固定化β-半乳糖苷酶,研究了固定化酶的制备条件、微观结构及酶学性质,结果表明:固定化时间为4 h,[酶]/[载体]=1:15(g:g)时,固定化酶的活力最高为0.517 U/g。红外光谱和扫描电镜对固定化酶的微观结构研究表明,双醛氧化纤维素的醛基与β-半乳糖苷酶的氨基发生共价反应形成固定化酶。与游离酶相比,β-半乳糖苷酶经过固定化后热稳定性和耐酸碱性增强,米式方程分析表明,β-半乳糖苷酶经固定化后与底物的亲和力降低,固定化酶重复使用5次后,相对酶活力为63%。     

Purification and some properties of polyphenoloxidase in eggplant (Solanum melongena)

Polyphenoloxidase (EC 1.10.3.1) in eggplant (Solatium melongena L) was purified by ammonium sulphate fractionation, DEAE-Cellulofine and DEAE-Toyopearl chromatography and Sephadex G-100 gel filtration. The enzyme was purified about 110-fold with a recovery of 5%. The purified enzyme more quickly oxidised chlorogenic acid (5-caffeoylquinic acid, IUPAC) than 10 other substrates used. The K_m value for the enzyme was found to be 0·50 mM with respect to chlorogenic acid; the optimum pH of the enzyme was about 4 with enzyme stability between pH 5 and 8. The enzyme was completely inactivated after heat treatment at 75°C for 30 min or 80°C for 5 min. Sodium metabisulphite, potassium cyanide and sodium fluoride markedly inhibited the enzyme activity.     

介孔材料SBA-15固定化胰蛋白酶的研究

在酸性条件下以正硅酸乙酯(TEOS)为硅源、非离子表面活性剂Pluronic P123为模板剂合成了介孔分子筛SBA-15,将其作为载体,对胰蛋白酶进行了固定化研究.研究了固定化条件对固定化酶量的影响,以及固定化酶的热稳定性和操作稳定性.结果表明,当酶液浓度大于5 mg/mL,固定化时间10 h时,胰蛋白酶的固定化效果最好,固定化酶量可达23.6 mg/g.固定化酶的热稳定性与游离酶相比有了显著的提高,且固定化酶具有较好的操作稳定性,连续反应6批次后,酶的剩余活性仍保持在40 %以上.     

双醛氧化纤维素固定化木瓜蛋白酶及酶学性质的研究

以双醛氧化纤维素为载体固定化木瓜蛋白酶,研究了固定化酶的制备条件、微观结构及酶学性质。结果表明:固定化时间4h,固定化温度4℃,酶/载体=1:3000(g:g)时,固定化酶的活力最高为50.9U/g。红外光谱和扫描电镜对固定化酶的微观结构研究表明,双醛氧化纤维素的醛基与木瓜蛋白酶的氨基发生共价反应形成固定化酶。与游离酶相比,木瓜蛋白酶经过固定化后,热稳定性和耐酸性增强,与底物酪蛋白的亲和力降低,固定化酶重复使用5次后,相对酶活力为55.1%。     

FAD为辅基的葡萄糖脱氢酶发酵、纯化及酶学性质

细菌来源的FAD为辅基的葡萄糖脱氢酶(FAD-GDH)较为罕见,作者利用乳糖为诱导剂,发酵E.coli BL21(DE3)生产FAD-GDH。7.5 L发酵罐中培养该菌,通过分批补料,分阶段温度控制,酶活达到1341 U/L,菌体量达12.4 g/L。通过镍柱、脱盐柱、阴离子交换柱三步层析对粗酶液分离纯化,获得比酶活109 U/mg的重组酶。SDS-PAGE凝胶电泳显示,重组蛋白质纯化后呈单一条带,相对分子质量约60000。等电聚焦电泳检测酶的等电点pI为5.3。酶标仪全波长扫描吸收光谱表明,该酶的辅基为FAD,与酶非共价键结合。相比其它糖类,以葡萄糖为底物酶的Km最小,为2.56 mmol/L,kcat/Km为3487.7 L/(mmol·s)。该酶在pH 5.5~8.0内稳定,最适反应pH 7.0,当pH高于8.0时酶活迅速降低。差式扫描量热分析(DSC)测得酶的Tm值为77℃,热稳定性良好。本研究为该酶的进一步工业化生产应用提供参考与借鉴。     

A thermostable histamine oxidase from Arthrobacter crystallopoietes KAIT-B-007

A thermostable histamine oxidase (EC 1.4.3.-) was found in cells of Arthrobacter crystallopoietes KAIT-B-007 isolated from soil. The enzyme was purified about 715-fold over the cell free extracts with a yield of 55% by ammonium sulfate fractionation and various column chromatographies. The purified enzyme was homogeneous on polyacrylamide gel-electrophoresis (native-PAGE). When the enzyme was kept at 65 degrees C and 70 degrees C for 10 min, the activity was fully stable at 65 degrees C and decreased to 9% of the initial level at 70 degrees C. The enzyme was very thermostable. The optimum pH for histamine oxidase activity was found to be at 9.0, and the enzyme was stable over the pH range of 6 to 9. The purified enzyme showed a single protein band on SDS-PAGE and its molecular mass was estimated to be about 81 kDa. The enzyme showed potent activity toward histamine, whereas it was inactive toward putrescine, cadaverine, spermine, and spermidine. Histamine oxidase was inhibited by N,N-diethyldithiocarbamate (DDTC). The inactive enzyme was restored with Cu2+ to 65% of the initial activity, but Cu+ did not enhance the enzyme activity. It is suggested that Cu2+ is essential for expression of histamine oxidase activity. The enzyme was a copper-containing protein having one atom of copper per mol of the enzyme protein as a result of atomic absorption analysis. The N-terminal amino acid sequence of the purified enzyme was different from that of histamine oxidase from Arthrobacter globiformis IFO12137.