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11.
纳米级金膜微电极的制作,表征及异相催化反应 总被引:1,自引:0,他引:1
报道了纳米级金膜微电极的制作方法,用XPS及SEM对电极表面进行了表征,考察了该电极的循环伏安及计时电流特性,在聚吡咯修饰微带金电极上成功地实现了葡萄糖氧化酶和电子传递媒体Fe(CN)6^3-的同时固定,并研究了GOD/Fe(CN)6^3-/PPy微酶电极对葡萄糖的响应,稳态响应电流与葡萄糖浓度之间存在Michealis-Menten动力学特征。 相似文献
12.
The thermodynamics of the conversion of aqueous glucose to fructose has been investigated using both heat conduction microcalorimetry
and high pressure liquid chromatography (HPLC). The reaction was carried out in both aqueous Tris/HCl buffer and in aqueous
phosphate buffer in the pH range 7–8 using the enzyme glucose isomerase and the cofactors CoCl2 and MgSO4. The temperature range over which this reaction was investigated was 298.15–358.15 K. We have found that the enthalpy of
reaction is independent of pH over the range investigated. A combined analysis of both the HPLC and microcalorimetric data
leads to the following results at 298 15 K:ΔG° = 349 ± 53 J mol-1, ΔH° = 2.78 ± 0.20 kJ mol-1, and ΔC
p
°
= 76 ± 30 J mol-1 K-1. The stated uncertainties are based upon an analysis of both the random and systematic errors inherent in the measurements.
Comparisons are made with literature data. The percent conversion of glucose to fructose has been calculated for the temperature
range 300–373.15 K. 相似文献
13.
Two guanidino acid oxovanadium(Ⅳ) complexes have been synthesized. Preliminary tests in vivo have shown that the two title complexes all display lowering glucose activity in vivo to STZ-rats. The effect of glucose-lowering of guanidino acetic acid oxovanadium(Ⅳ) complex in vivo is higher than that of guanidino propanoic acid oxovanadium(Ⅳ) complex. 相似文献
14.
15.
Cellulase retention and sugar removal by membrane ultrafiltration during lignocellulosic biomass hydrolysis 总被引:1,自引:0,他引:1
Technologies suitable for the separation and reuse of cellulase enzymes during the enzymatic saccharification of pretreated
corn stover are investigated to examine the economic and technical viability of processes that promote cellulase reuse while
removing inhibitory reaction products such as glucose and cellobiose. The simplest and most suitable separation is a filter
with relatively large pores on the order of 20–25 mm that retains residual corn stover solids while passing reaction products
such as glucose and cellobiose to form a sugar stream for a variety of end uses. Such a simple separation is effective because
cellulase remains bound to the residual solids. Ultrafiltration using 50-kDa polyethersulfone membranes to recover cellulase
enzymes in solution was shown not to enhance further the saccharification rate or overall conversion. Instead, it appears
that the necessary cellulase enzymes, including β-glucosidase, are tightly bound to the substrate; when fresh corn stover
is contacted with highly washed residual solids, without the addition of fresh enzymes, glucose is generated at a high rate.
When filtration was applied multiple times, the concentration of inhibitory reaction products such as glucose and cellobiose
was reduced from 70 to 10 g/L. However, an enhanced saccharification performance was not observed, most likely because the
concentration of the inhibitory products remained too high. Further reduction in the product concentration was not investigated,
because it would make the reaction unnecessarily complex and result in a product stream that is much too dilute to be useful.
Finally, an economic analysis shows that reuse of cellulase can reduce glucose production costs, especially when the enzyme
price is high. The most economic performance is shown to occur when the cellulase enzyme is reused and a small amount of fresh
enzyme is added after each separation step to replace lost or deactivated enzyme. 相似文献
16.
羧基功能化的聚[(9,9-二辛基芴基-2,7-二基)-co-(1,4-苯并-{2,1′,3}-噻二唑)]聚合物点(PFBT-COOH)在无外加共反应试剂的条件下具有高的电致化学发光(ECL)信号,且过氧化氢(H_2O_2)对其ECL具有高效猝灭作用。采用PFBT-COOH修饰玻碳电极,进一步交联葡萄糖氧化酶(GOD)以构建酶传感器(GOD/PFBT-COOH/GCE)。随着检测底液中葡萄糖浓度的增加,葡萄糖在GOD催化下原位产生的H_2O_2量增加,导致传感器的ECL信号逐渐减弱,从而实现葡萄糖的准确、快速、灵敏检测。此方法测得葡萄糖的线性范围为1.0×10~(-7)~3.0×10~(-3) mol/L,检出限为3.0×10~(-8) mol/L。血清样品中葡萄糖的加标回收率为98.5%~106%。该策略为酶传感器的构建提供了新思路,为葡萄糖的检测提供了新方法。 相似文献
17.
The present short review deals with electroanalytical aspects of electrochemical response of ascorbic acid (Vitamin C) at conducting and electrogenerated polymer modified electrodes. Two main topics are considered: (i) electrocatalytic oxidation of ascorbate at conducting polymer modified electrodes, leading to electroanalytical techniques for ascorbate assay, and (ii) retardation of ascorbate penetration through a layer of electrogenerated polymers, leading to permselective coatings and their diverse uses, especially for biosensing devices. 相似文献
18.
葡萄糖氧化酶电极的制备 总被引:5,自引:0,他引:5
葡萄糖氧化酶电极的制备于秀娟,周定,郭京华(哈尔滨工业大学应用化学系哈尔滨150006)关键词葡萄糖氢化酶,酶电极,制备酶与电极的连接即酶膜的形成是制备酶电极的关键步骤之一,有许多种方式[1~9].葡萄糖氧化酶(GOD)电极是研究较早和报道较多的一类... 相似文献
19.
Comparison of different strains of the yeastYarrowia lipolytica for citric acid production from glucose hydrol 总被引:3,自引:0,他引:3
Maria Wojtatowicz Waldemar Rymowicz Helena Kautola 《Applied biochemistry and biotechnology》1991,31(2):165-174
Four commercial strains and two mutants of the yeast species Yarrowia lipolytica were screened using batch fermentation. Strain Y. lipolytica A-101-1.14 (induced with UV irradiation) was found to be the most suitable for citric acid production from glucose hydrol (39.9% glucose and 2.1% other sugars), a byproduct of glucose production from potato starch. The specific rate of total citric and isocitric acid production was 0.138 g/g.h, the yield on consumed glucose 0.93 g/g, and the productivity achieved was as high as 1.25 g/L.h. All of the tested yeast strains were able to utilize only the glucose from the glucose hydrol medium. Thus, some residual higher oligosaccharides remained in the process effluent. 相似文献
20.
The solubility of the nucleic acid bases, adenine and thymine, in aqueous erythritol, xylose, glucose, and sucrose solutions has been studied. The solubility of adenine increases linearly with glucose and sucrose concentration, whereas with the other reagents a nonlinear increase is observed. Below 1.5M reagent concentration, the solubility of adenine increases in the order erythritol < robose, xylose < glucose < sucrose. The solubility of thymine in these solutions, on the other hand, decreases, increases, or does not change depending upon the reagent. The effect of temperature on the solubility of adenine and thymine in sugar solution indicates that the transfer of these molecules from water to sugar solution is exothermic.Presented in part at the VIIth All-India Symposium in Biophysics held at Visva Bharati University during October 1976. 相似文献