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利用环氧树脂载体进行固定化转氨酶的研究,通过单因素优化确定了较优的酶固定化条件:ES-103b树脂载体、转氨酶和辅酶磷酸吡哆醛最佳质量比为50:6:5,在pH为7.0的1mol/L磷酸钾缓冲液介质中吸附25 h.将得到的固定化颗粒重新置于pH为9.0的100 mmol/L磷酸钾缓冲液中,30℃保温30 h.取出后置于pH为8.5的3 mol/L甘氨酸-NaOH缓冲液中,25 ℃保温12h,制得固定化转氨酶,其比活力为52.7 U/g(湿载体),酶活回收率达到49.3%.酶学性质研究表明:固定化转氨酶催化反应最适pH、温度分别为7.0、50℃;固定化酶热稳定性及pH稳定性明显提高,50℃条件下的半衰期为20.2 d;在pH 8.0的三乙醇胺缓冲液中(4℃),10 d后酶活仍保持初始酶活的82.3%. 相似文献
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以枯草芽孢杆菌基因组为模板通过PCR扩增获得谷氨酰胺酶基因ylaM,构建重组质粒p MA5-ylaM,将其转化到枯草芽孢杆菌168中获得重组菌BS168/pMA5-ylaM,并在宿主菌成功得到表达,纯化后的谷氨酰胺酶比酶活大小为939.48 U/mg。谷氨酰胺酶的反应最适pH为7.5,反应最适温度为55℃,La~(3+)、Zn~(2+)、Fe~(3+)和Al~(3+)对谷氨酰胺酶活力具有一定的抑制作用,在NaCl浓度为15%~17.5%的条件下,该酶酶活力可以保留50%以上。在5 L罐中,通过分批补料发酵,其最高酶活力产量为215.06 U/mL。 相似文献
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茂源链霉菌(Streptomyces mobaraensis)谷氨酰胺转氨酶(transglutaminase,TGase)活化蛋白酶(activating metalloprotease,TAMEP)能够专一性切割TGase的酶原区,其高效制备对于重组TGase的生产有重要意义。将S.mobaraensis来源的TAMEP成功表达于大肠杆菌。通过对信号肽类型、信号肽N端密码子及诱导表达条件的优化,使胞外TAMEP酶活力达到186.3 U/mL。酶学性质分析显示,重组TAMEP的最适反应温度和最适反应pH分别为55℃和7.0; TAMEP在30~50℃孵育60 min酶活力保持在50%以上,且在pH 6.2~8.9较稳定; 0.133μmol/L重组TAMEP能够在30 min内使6.91μmol/L TGase基本活化。研究结果为TAMEP规模化制备提供了生产菌株和基础数据。 相似文献
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茂原链轮丝菌Streptoverticilliummobaraense所产生的谷氨酰胺转胺酶发酵液通过抽滤、超滤、乙醇沉淀、离心和冷冻干燥,制得粗酶粉的酶活约为1033U/g.对粗酶研究发现,该酶的最适反应温度为52℃,最适pH为6.0;粗酶的pH稳定范围在4~8,温度稳定范围在20~40℃,离子强度对该酶的活性稍有影响.粗酶经CM 纤维素层析和SephadexG 75凝胶过滤层析后得到较纯的酶,通过SDS 聚丙烯酰胺凝胶电泳检验蛋白质纯度,得到较弱的单一区带.其中,CM 纤维素层析的纯化倍数为4.5,收率质量分数约为78.8%;凝胶过滤层析纯化倍数为1.11,收率质量分数为50%;用凝胶过滤法测得谷氨酰胺转胺酶的相对分子质量为40092. 相似文献
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香菇中部分纯化β-葡萄糖苷酶的酶学性质 总被引:1,自引:0,他引:1
对β-葡萄糖苷酶的酶源进行了筛选,以求得到高产量、高稳定性的酶源。研究发现,香菇中β-葡萄糖苷酶含量较高。本论文对香菇中β-葡萄糖苷酶进行了提取、硫酸铵沉淀分离和酶学性质的研究,该酶被纯化了2.75倍。该酶反应的最佳温度为60℃,最佳pH为4.0;在pH为3.0~5.0和低于50℃时较稳定;80℃时酶活性基本丧失。1mmol/L的Ag 存在使酶活力完全丧失。10%的有机溶剂甲醇、乙醇、丙酮、2-丙醇等都明显抑制酶活性。 相似文献
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Transglutaminase (TGase) was separated from the culture broth of an isolated strain of Streptoverticillium mobaraense. The crude enzyme was prepared by centrifugation, ultrafiltration, precipitation by alcohol, centrifugation and freeze‐drying. The yield after these processes was 65–70%. Then the enzyme was purified to homogeneity by chromatography on CM‐cellulose and Sephadex G‐75 on which the yields were about 70% and 80%, respectively; the purified folds reached 2.5–4.7 and 1.08–2.06, respectively. The molecular weight of this TGase was 39,500–40,100 Da by gel filtration chromatography. Optimum enzyme activity was observed in the pH range of 5.0–7.0, and it was maintained stable at 20–40C. The optimal temperature and pH was 52C and 6.0, respectively. At 1 mM and 5 mM metal ion or inhibitors concentration, TGase activity was strongly inhibited by Zn2+ and NEM, and not affected obviously by Ba2+, Ca2+, Co2+, Cu2+, Fe2+, Fe3+, Mg2+, Mn2+, Na+ as well as PMSF and EDTA. The effects of these additions on this TGase were compared with those of other microbial TGases. 相似文献
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香菇中一种抗氧化活性成分的分离及组成分析 总被引:1,自引:0,他引:1
香菇全体经浸提,匀浆,脱色等预处理,经DEAE纤维素柱及Ultrogel ACA-44凝胶柱层析得到一种具有高抗氧化活性的成分(Le-Ⅱ).其浓度为1 g/L时可完全清除1,1-二苯基苦基苯肼自由基(DPPH).Le-Ⅱ红外扫描有典型的多糖和蛋白质的吸收峰.氨基酸分析表明其氨基酸种类齐全,其中酸性氨基酸与中性氨基酸较多,蛋白质质量含量为14.29%.气相色谱测得单糖组成为鼠李糖,阿拉伯糖,甘露糖,葡萄糖,摩尔比为0.58:0.67:0.78:3.69.多糖质量含量为1.29%.β-消去反应表明Le-Ⅱ中存在O-型连接的糖蛋白.刚果红反应初步表明其多糖部分存在三股螺旋构象. 相似文献
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ABSTRACT
This work aimed to evaluate the antioxidant activity of Lentinus edodes and Agaricus blazei mushrooms, as well as to measure the content of total phenolic compounds of mushroom extracts and verify the oxidative stability of soybean oil added with mushroom extracts that showed higher antioxidant activity according to the methods of the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH•) free radical scavenging and the β‐carotene/linoleic acid system. According to the DPPH• method, the maximum antioxidant activity for L. edodes and A. blazei methanol extracts was 92.84 and 95.10%, respectively. For the β‐carotene/linoleic acid system, the highest values of antioxidant activity were 93.06% for L. edodes and 78.96% for A. blazei. The content of total phenolic compounds ranged from 7.21 to 128.44 and 26.67 to 134.67 mg gallic acid equivalent/g for L. edodes and A. blazei, respectively. The oxidative stability values provided by the Rancimat method indicated that the two varieties presented similar induction period of 19.85 h.PRACTICAL APPLICATIONS
Mushrooms present high content of antioxidant compounds that are capable of reducing the harmful effects of free radicals. Among the antioxidants present in mushrooms, phenolic compounds stand out as phenolic acids, flavonoids and tocopherols. To decrease or prevent lipid oxidation, synthetic antioxidants are used as food additives. Nevertheless, studies have revealed that these compounds are likely to pose risks to human health. The concern regarding the safety of synthetic antioxidants has motivated the search of natural antioxidants that can substitute them totally or partially.14.
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微波法与传统热水法提取香菇多糖的比较研究 总被引:20,自引:3,他引:20
以香菇多糖为研究对象,采用单因素分组实验法对香菇多糖提取工艺(热水法和微波提取法)进行了初步的探讨,比较了时间,浸取温度,浸取次数,液固比等因素对多糖提取率的影响。其中传统热水提取法的最佳工艺条件为:液固比10,加热温度45℃,加热时间5h,提取二次。微波法提取香菇多糖的最佳工艺条件:液固比10,功率40%,加热时间180s,pH值1。通过两种最佳工艺条件的结果比较可知,微波萃取法具有节能、省时、环保、操作便利且提取率高等优点。 相似文献
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采用丙酮分级沉淀和DEAE-纤维素柱层析方法,从兔血红细胞中提取分离到高纯度的超氧化物歧化酶,琼脂糖凝胶电泳和醋酸纤维素薄膜电泳的均显示一条谱带,其等电点为pH=4.8,最大紫外光吸收波长为262nm,比活力为5668u/mlProt.浓度为15ug/mL的酶溶液在50℃放置30min,活力保持76%,表明其热稳定性较高。 相似文献
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