首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到19条相似文献,搜索用时 109 毫秒
1.
以戊二醛活化的DEAE纤维素为载体,采用共价键法固定化MethylomonasZ201细胞.固定化细胞催化丙烯环氧化的最优细胞/载体比为32mg干重细胞/(gDEAE纤维素),最适pH值和最适温度分别为7.8和35℃.用纯氧代替空气作为氧源,分别使游离和固定化细胞的MMO活性提高了8%和35%.外源性电子给体甲酸钠对固定化细胞MMO活性的激发作用小于游离细胞.失活动力学分析结果表明,固定化细胞的稳定性高于游离细胞.  相似文献   

2.
夏仕文  尉迟力 《分子催化》1997,11(4):273-277
以戊二醛活化的DEAE-纤维素为载体,采用共价键法固定化MethylomonasZ201细胞,固定化细胞催化丙烯环氧化的最优细胞/载体比为32mg干重细胞,最适PH值达温度分别为7.8和35℃,用纯氧代替空气作为氧源,分别使游离和固定化细胞的MMO活性提高了8%和35%,外泊性电子给体甲酸钠对固定化细胞MMO活性的激发作用小于游离细胞,失活动力学分析结果表明,固定化细胞的稳定性高于游离细胞。  相似文献   

3.
降解溴氨酸的鞘氨醇单胞菌N1菌株的固定化研究   总被引:2,自引:0,他引:2  
用聚乙烯醇(PVA)做载体,用包埋法固定降解溴氨酸(学名为1-氨基-4-溴蒽醌-2磺酸,简称ABA)的鞘氨醇单胞菌(Sphingomonas sp.)N1菌株,并对固定化菌的制备条件及固定化菌降解溴氨酸的一般性质进行了研究.实验结果表明,细胞固定化以后的溴氨酸降解速度明显高于游离细胞,反应遵循一级反应动力学,反应的最适pH和温度范围明显变宽.固定化细胞的储存稳定性也高于游离细胞,4℃储存50d后,其对溴氨酸的降解率仍在99%以上,而游离细胞仅为7.4%.固定化细胞经过50次重复使用后,对溴氨酸仍具有很高的降解活性.  相似文献   

4.
研究了利用无机载体(活性炭、氧化铝、分子筛等)吸附法和天然藻胶(海藻酸钙等)包埋法制备的固定化甲烷氧化细菌的催化性能及其在生物反应器中的反应,结果表明,在进行甲烷制甲醇的反应中、活性炭吸附制备的固定化细胞的操作稳定性最好,但其初始酶活性与休止游离细胞相比损失了60% ̄80%,海藻酸钙包埋的固定化细胞初始酶活性高(与游离细胞相比,可保持55% ̄90%的酶活性),但反应中甲醇累积速度很低,而双重介质(  相似文献   

5.
以水热法于ZSM-5分子筛中分散MoO3的研究   总被引:6,自引:1,他引:6  
热扩散法的MoO3最高分散量为每克ZSM-5上0.08克MoO3.而本文采用水热分散法可使MoO3在ZSM-5分子筛中的分散量大大提高.当分散量高达每克ZSM-5上0.3克MoO3时,通过XRD,IR,DTA谱测试和吸附测定,都证实了MoO3在ZSM-5中仍然是以非晶相分散态存在.此时,样品有吸附自重6%的水的吸附能力和相应的孔道.  相似文献   

6.
固定化根霉细胞催化拆分(R,S)-环氧丙醇丁酸酯的研究   总被引:3,自引:0,他引:3  
用聚乙烯醇包埋、硫酸钠固定法对根霉( Rhizopussp.Bc0-09)菌体细胞进行了固定化,所得凝胶具有良好的机械性和稳定性. 对固定化细胞催化( R,S)-环氧丙醇丁酸酯水解反应的性能进行了研究. 对pH值的影响考察结果表明, 30 ℃下, 反应初速度在pH 值为5.5 时最大; 酶的立体选择性在pH值为5.5~6.0 时最高, 对映体比率( E值)为57. 对温度的影响考察结果表明,pH 值为5.5, 反应初速度在55 ℃时最大; 酶的立体选择性随温度升高而下降. 固定化细胞具有较好的操作稳定性.  相似文献   

7.
甲烷单加氧酶的催化机理   总被引:5,自引:0,他引:5  
研究了来源于Methylomonassp.GYJ3菌的甲烷单加氧酶(MMO)催化机理,结果表明,用还原剂处理基于酶可得么不同还原态的羟基化酶,其中全还原态的羟基化酶具有MMO催化活性,还原酶和调节蛋白单独存在的均没有MMO活性,确定了羟基化酶组分是MMO的催化活性中心,用紫外光谱法证实了NADH和还原酶之间的相互作用,即还原酶接受NADH的电子,使氧化态的FAD转化为还原态的FAD,MMO的电子传  相似文献   

8.
CuY和Cu-ZSM-5催化剂上NO直接分解活性及活性中心的研究   总被引:2,自引:0,他引:2  
研究了CuY,Cu-ZSM-5分子筛制备条件对NO直接分解活性的影响.结果表明,在不同酸碱度下交换的CuY分子筛,在pH=9时活性较好,而Cu-ZSM-5型在pH=7时较好.随交换度提高,Cu-ZSM-5活性上升,而CuY交换度达45%后活性趋于平稳:用DTA,TPD,XPS及IR等技术,对活性中心进行了研究,表明钢是以水合离子形式与分子筛中Na+进行交换.Cu-ZSM-5的活性位单一,CuY上则有两种NO吸附位.经400℃焙烧后,铜优先占据Y的β笼,此即活性位.未经焙烧的样品中铜主要以Cu2+存在.400℃抽空处理产生Cu+.讨论了NO在含铜样品表面的反应过程.  相似文献   

9.
甲烷单加氧酶的催化性能   总被引:3,自引:0,他引:3  
研究了来源于ethylomonas sp.GYJ3菌的甲烷单加氧酶(MMO)的催化性能,结果表明,当组成该酶的三个组分,羟基化酶、调节蛋白B和还的酶的摩尔比为1:1.7:2.0时,重组的MMO体系酸疼的比活最高,为342nmol/(mg.min),当反应体系的PH在6.5-7.5时,MMO酶的活力最大,研究了纯MMO催化甲烷羟基化反应作丙烯环氧化反应的特性,以及金属离子和电子本对MMO催化反应的影  相似文献   

10.
HPD-750树脂是中极性大孔吸附树脂,生物相容性好,机械性能稳定,具有较大的比表面积,可用于固定化酶载体材料。本文以HPD-750大孔树脂为载体固定化果胶酶,研究各因素对固定化酶的影响,并采用正交试验对固定化条件进行优化。结果表明,当pH为4.0、固定化温度为45℃、固定化时间为4h、加酶量为0.16g/mL时,固定化酶活力可达5146U/mg。以HPD-750大孔树脂为载体材料制备的固定化酶相较于游离酶具有更好的酸碱稳定性和热稳定性。在循环使用10次后,酶活力依然保留80%以上;4℃储藏25d之后,其酶活力仍保留60%以上。与D311大孔树脂、聚丙烯酰胺和海藻酸钠微球制备的固定化酶相比,HPD-750大孔树脂固定化酶的活性、操作稳定性、机械稳定性和储存稳定性都较好。该结果说明,HPD-750大孔树脂可作为固定化酶较好的载体材料。  相似文献   

11.
An investigation was conducted to determine whether immobilized resting cells of Streptomyces clavuligerus NP1, entrapped on a polymeric matrix, are able to perform oxidative ring expansion of benzylpenicillin into deacetoxycephalosporin G by virtue of their deacetoxycephalosporin C synthase (“expandase”) activity. Cells entrapped in polyethyleneimine-barium alginate (1.5%) were able to sustain activity for at least four 2-hcycles, whereas free resting cells were inactive after the second cycle. Although entrapped cells exhibited lower oxidative ring expansion activity than free resting cells, immobilization may offer storage stability, recyclability, and operational stability for biotransformation of penicillins to cephalosporins, thus contributing to the development of a biological means for the production of the important industrial intermediate 7-aminodeacetoxycephalosporanic acid.  相似文献   

12.
Aspergillus niger NRC 107 xylanase and β-xylosidase were immobilized on various carriers by different methods of immobilization, including physical adsorption, covalant binding, ionic binding, and entrapment. The immobilized enzymes were prepared by physical adsorption on tannin-chitosan, ionic binding onto Dowex-50W, covalent binding on chitosan beads through glutaraldehyde, and entrapment in polyacrylamide had the highest activities. In most cases, the optimum pH of the immobilized enzymes were shifted to lower than those of free enzymes. The optimum reaction temperature of immobilized xylanase was shifted from 50°C to 52.5–65°C, whereas that of immobilized β-xylosidase was shifted from 45°C to 50–60°C. TheK m values of immobilized enzymes were higher than those of native enzymes. The operational stability of the immobilized enzymes was evaluated in continuous operation in packed-bead column-type reactors. The enzymes covalently bounded to chitosan showed the highest operational stability. However, the enzymes immobilized by physical adsorption or by ionic binding showed a low operational stability. The enzymes entrapped in polyacrylamide exhibited lower activity, but better operational stability.  相似文献   

13.
本文报导了在 Methylosinus trichosporium 3011细胞反应液中加入一些化学物质对甲醇累积的影响。结果表明,Na~+抑制甲烷单加氧酶的活性。当 M.trichosporium 3011细胞反应液中含高浓度磷酸根时,只有很少量甲醇累积下来。EDTA 和 Na_2EDTA 甲醇累积的促进作用小于甲酸钠或甲酸的作用。但由于 EDTA 不仅可以抑制甲醇脱氢酶的活性,而且可以螯合 Na~+,而甲酸则可使 NADH 辅酶再生。因此,反应液中含有2mM EDTA 和20mM 甲酸时甲醇累积量最高。  相似文献   

14.
采用修饰与未修饰单壁碳纳米管固定C-C键水解酶BphD,并对固定化酶的相对活性、稳定性、重复使用性进行了考察.结果表明,未修饰单壁碳纳米管固定的BphD相对活性为游离态的52.5%,其热稳定性和在变性剂中的稳定性均有所提高,且重复使用10次仍可保持初始活力的90%.修饰单壁碳纳米管固定的BphD相对活性可达99.7%,但其稳定性没有明显提高.同源模建及分子对接分析结果显示,未修饰的单壁碳纳米管对BphD亚基之间的联系可能存在干扰作用,从而对其活性产生影响.  相似文献   

15.
The yeastSaccharomyces cerevisiae was entrapped within polyacrylamide gel beads by employing a procedure that uses sodium dodecylsulfate as a detergent to improve the spherical configuration of the beads. The resulting preparation showed a rate of fumarate bioconversion to L-malic acid about 60 times higher than that found for the free cells. Almost all fumarate was converted in 30 min of incubation. The thermal stability of the immobilized cells did not significantly differ from the free cells. An optimal pH of 5.7 was found for the immobilized preparation and no succinic acid was detected as a by-product in the incubation mixture.  相似文献   

16.

Aureobasidium pullulans cells with fructosyltransferase activity were immobilized in 2% calcium alginate beads, and the production of fructo-oligosaccharides from sucrose was studied in a stirred tank bioreactor. It was found that cells ofA. pullulans were entrapped evenly on the alginate matrix of 2.2 mm in diameter, and an effectiveness factor of the beads was determined to be 0.3. By comparison with the system of free cells in batch operation, the total amount of fructo-oligosaccharides produced by immobilized cells was similar although the composition of fructo-oligosaccharides was found to be different. In semibatch operation with immobilized cells, reproducible results up to 60 cycles were obtained at 50 °C and this operation resulted in no loss of activity of immobilized cells.

  相似文献   

17.
以纳米金溶胶(NGS)和多重壁碳纳米管(MWCNTs)的共混物(NGS/MWCNTs)作为固定漆酶的载体,研究了3种固定漆酶方法在酶固定量、比活力上的差异。研究了不同的固定方法对固定酶热稳定性和重复使用性及纳米金溶胶颗粒粒径对酶固定量和固定酶动力学参数的影响。实验结果表明,NGS/MWCNTs具有良好的固定漆酶能力和高固酶比活力,NGS/MWCNTs(NGS粒径37nm)通过简单物理吸附法固定漆酶的量和固酶的比活力最高,分别可达33.80mg/g和9.433U/mg。在NGS/MWCNTs上采用化学键合方法固定的漆酶在70℃放置2h后仍然保持初始活力的75%,重复使用20次后仍保持初始活力的70%。纳米金溶胶粒子越小(24nm),底物和固定漆酶间亲和力越好(KM=0.027mmol/L),表观速率常数越大。  相似文献   

18.
Rhizopus oryzae immobilized in calcium alginate was applied in lactic acid fermentation with unhydrolyzed raw sweet potato powders as the sole carbon source. The effects of sodium alginate concentration, calcium chloride concentration, and the immobilized bead diameter on lactic acid production were investigated. Increase in sodium alginate concentration during the gelation process would harden the immobilized capsule, which led to a decrease in lactic acid production. The increase in calcium chloride would increase the thickness of the immobilized capsule, which would increase the mass transfer resistance. Nevertheless, while the calcium chloride was lower than 15%, it would not have obvious effects on lactic acid production. A larger bead could have more space for cell growth, which led to the maximum lactic acid production observed at the 5-mm bead diameter. Moreover, results of repeated-batch operation suggested that immobilized cells could have higher stability in lactic acid production than free cells. The total cumulative lactic acid in immobilized-cell operation could increase by 55% as compared with free-cell operation after 216 h (seven repeated-batches), and no loss of amylolytic activity was observed. The results indicated that immobilized R. oryzae by Ca-alginate could be suitable for lactic acid production from unhydrolyzed raw potato powders.  相似文献   

19.
A novel immobilized enzyme system supported by poly(acrylic acid/N,N’-methylene-bisacryl-amide) hydrogel microspheres was prepared. This system exhibited characteristics of reversible pH-triggered release. The morphology, size, and chemical structure were examined through optical microscopy, particle size analyzer, and Fourier transform infrared spectrometer. Immobilization and release features were further investigated under different conditions, including pH, time, and microsphere quantity. Results showed the microspheres were regularly spherical with 3.8 ~ 6.6 μm diameter. Loading efficiencies of bovine serum albumin immobilized by gel entrapment and adsorption methods were 93.9% and 56.2%, respectively. The pH-triggered protein release of the system occurred when medium pH was above 6.0, while it was hardly detected when medium pH was below 6.0. Release efficiencies of entrapped and adsorbed protein were 6.38% and 95.0%, respectively. Hence, adsorption method was used to immobilize trypsin. Loading efficiency of 77.2% was achieved at pH 4.0 in 1 h. Release efficiency of 91.6% was obtained under optimum pH catalysis condition set at 8.0 and trypsin was free in solutions with retention activity of 63.3%. And 51.5% of released trypsin could be reloaded in 10 min. The results indicate this kind of immobilized enzyme system offers a promising alternative for enzyme recovery in biotechnology.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号