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761.
762.
Eun Gyo Lee Hye Soon Won Hyeon-Su Ro Yeon-Woo Ryu Bong Hyun Chung 《Journal of Molecular Catalysis .B, Enzymatic》2003,26(3-6):149-156
Esterase PF1-K from Pseudomonas sp. KTCC 10122BP was overproduced by the fed-batch culture of Escherichia coli. The soluble expression of esterase PF1-K was achieved by shifting the culture temperature from 37 to 25 °C at the time of IPTG induction. The enzyme was partially purified to about 75% purity by a single-step hydrophobic interaction column chromatography. The purified enzyme exhibited a fairly high enantioselectivity towards the hydrolysis of rac-flurbiprofen ethyl ester. The enzymatic chiral resolution was further improved by optimizing the reaction conditions in terms of reaction rate and enantioselectivity. The optimal reaction conditions were found to be 40 °C, pH 10.5 and 600 mM of initial rac-flurbiprofen ethyl ester. After 90 min of batch reaction under the optimal conditions, 50% of the initial rac-flurbiprofen was hydrolyzed with an enantiomeric excess of 99%. 相似文献
763.
764.
黑木耳种内杂交子的鉴定技术* 总被引:5,自引:0,他引:5
采用原生质体技术,获得黑木耳(Auricularia auricula)栽培菌株He-1的单核化菌株H1、H2、H3和栽培菌株Ju-1的单核化菌株J1、J2、J3,将H1、H2、H3分别与J1、J2、J3配对杂交,核相观察确认H2J1、H2J2和H2J3均为双核体。酯酶同工酶分析表明,H2J1、H2J2和H2J3不仅具有相应的亲本单核体共有的酶带,而且具有两个亲本各自的特异性标记酶带。RAPD分析表明,引物S30和S62对杂交子H2J1、H2J2和H2J3的扩增图谱中不仅包含相应的亲本单核体所共有的DNA带,而且包含亲本单核体各自的特异性DNA带。拮抗和栽培试验表明,杂交子H2J1、H2J2、H2J3与双核体亲本He-1和Ju-1的菌落之间有窄细的黑色拮抗线,子实体形态上有较明显差异。 相似文献
765.
苜蓿组织培养中球形胚发生时特异蛋白质和同工酶分析 总被引:10,自引:2,他引:8
试验在苜蓿组织培养中,对球形胚形成过程中特异蛋白质表达的模式、过氧化物酶及酯酶同工酶酶谱变化进行研究,结果表明:苜蓿组织培养中从胚性愈伤组织到球形胚发育的进程中,顺序消失和出现了11种中小分子量多肽;过氧化物酶同工酶酶谱发生了显著的变化;酯酶同工酶酶谱变化不大,但其总活力对于维持体细胞胚胎发生是必须的。 相似文献
766.
Maha Karra-Chaabouni Sylviane Pulvin Daniel Thomas Didier Touraud Werner Kunz 《Biotechnology letters》2002,24(23):1951-1955
The initial activity rate for the synthesis of geranyl butyrate by an esterase from Mucor miehei increased with increasing water activity and decreased above 0.5 water activity. The conversion yield after 75 h was about 75% for different, but low, initial water activities and decreased above 0.5 water activity. This behaviour is related to water-enzyme interactions. 相似文献
767.
Madoka Nakai Chie Goto† Takahiro Shiotsuki‡ Yasuhisa Kunimi 《Physiological Entomology》2002,27(2):157-164
Abstract Larvae of Adoxophyes honmai (Lepidoptera: Tortricidae) infected with granulovirus (AdhoGV) do not pupate; instead, they undergo prolonged larval development and die during the final stadium. Non-infected larvae, however, pupate after five larval stadia. Insect metamorphosis is regulated by fluctuations of ecdysteroid and Juvenile Hormone (JH). JH esterase activity and titres of ecdysteroid must be measured to understand fully the interaction of an insect virus and its host. JH esterase activity is consistently low in AdhoGV-infected larvae, which suggests that JH in AdhoGV-infected larvae is not degraded during the final stadium. The ecdysteroid titre in non-infected larvae showed a large peak in the final stadium before pupation, whereas that in AdhoGV-infected larvae increased from day 2 to day 5 in the final stadium, and then remained at a high level until death. Furthermore, an ecdysteroid UDP-glucosyltransferase (EGT) assay showed that this activity occurs in haemolymph from AdhoGV-infected larvae, but not in haemolymph of non-infected larvae. PCR and sequencing analysis revealed that the AdhoGV genome contains an egt gene, which encodes a protein of 445 amino acids, located approximately 1 kbp upstream from the granulin gene. These results suggest that AdhoGV-infected larvae are prevented from pupating because JHE activity is suppressed and EGT expression inactivates ecdysteroid in the haemolymph. 相似文献
768.
Neuropathy target esterase (NTE) is phosphorylated and aged by oraganophosphorus compounds (OP) that induce delayed neuropathy in human and some animals. NTE has been proposed to play a role in neurite outgrowth and process elongation during neural differentiation. However, to date, there is no direct evidence of the relevance of NTE in neural differentiation under physiological conditions. In this study we have investigated a possible role for NTE in the all-trans retinoic acid (ATRA)-induced differentiation of neuroblastoma cells by antisense RNA. A NTE antisense RNA construct was generated and then transfected into human neuroblastoma SK-N-SH cells. A positive cell clone that can stably express NTE antisense RNA was obtained by G418 selection and then identified by western blotting. NTE activity was depressed in the transfected cells with only about 50% activity of the enzyme in the control cells. ATRA-induced differentiation of the neuroblastoma cells with lowered NTE activity revealed that inhibition of NTE expression does not affect neural differentiation in SK-N-SH cells. The result suggested that organophosphates may inhibit neural differentiation by initially acting on other targets other than NTE. 相似文献
769.
Lipolysis of butter oil in a hollow fiber reactor containing an immobilized calf pregastric esterase was studied at 40 degrees C, a pH of 6.0, and glycerol concentrations of 0, 150, and 500 g/L in the buffer solution. The concentrations of 10 fatty acid species in the lipolyzed product were determined using high-performance liquid chromatography. The rate of loss of enzyme activity and the relative selectivities of this esterase depended on the glycerol concentration. By contrast, the overall rate of release of fatty acids was not affected by the glycerol concentration. Loss of enzyme activity was modeled using first-order kinetics. The models for deactivation and reaction kinetics were fit simultaneously to the data. The model was successful in describing the rates of release of all 10 fatty acid species for a range of space times from 0 to 25 h. The parameters of the model were tested for dependence on glycerol concentration. 相似文献
770.
The study was focused on changes of anatomical and histochemical parameters of buds of 4-year-old Norway spruce (Picea abies L. Karst) trees subjected to simulated acid rain (SAR). Solutions of pH 2.9 and 3.9 were applied by spraying on shoot and/or by watering for two years. No macroscopic changes of buds or needles were observed in connection with SAR application and the only induced change was 2-week earlier onset of bud break in all treated variants compared to the control. Two-year treatment caused decrease in number of leaf primordia and increase in number of living bud scales in treated dormant buds while these parameters remained unchanged in the control buds. Treatments with solution of pH 2.9 caused decrease of flatness of bud apical meristem during the vegetative season. Increased activity of non-specific esterase in treated buds occurred during dormancy and bud break and the enhanced accumulation of phenolic compounds was detected at the beginning of shoot growth. Changes in histochemical parameters of bud tissues were induced mainly by spraying of shoots and can thus be qualified as primary damage. 相似文献