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41.
Wakako Tsugawa Shuichi Horiuchi Mitsuharu Tanaka Hitoshi Wake Koji Sode 《Applied biochemistry and biotechnology》1996,56(3):301-310
A novel glucose dehydrogenase (GDH) from a marine bacteriumCytophaga marinoflava IFO 14170 was isolated from its membrane fraction. This GDH catalyzes the oxidation of a hydroxy group of glucose, but does
not react in its C-l position. This enzyme is composed of a single peptide with a mol wt of 67,000. The GDH can react under
high salinity. The optimum pH is around 8.0, showing a typical property of marine bacterial enzymes. Using this novel enzyme,
an enzymatic determination of 1,5-anhydro-D-glucitol (1,5AG) utilizing 2,6-dichrolophenolindophenol (DCIP) and phenazine methosulfate
(PMS) as electron mediators was caried out. A good linear correlation was observed from 0.5 mM to 4 mM of 1,5AG. 相似文献
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The preparation and characterization of an amperometric glucose biosensor based on the entrapment of glucose oxidase (GOx) in a polyacrylamide microgel is described. This study proves that polyacrylamide microgels provide an excellent matrix for GOx immobilization that can be used as a biological material in amperometric biosensors. The interference produced by ascorbic and uric acid has been eliminated by including acrylic acid in the polymeric matrix. With this modification, we obtain an adequate device for glucose determination in complex samples such as blood and serum. The study of the temperature effect in the response of biosensors indicates that swelling of the microgels directly influences the enzymatic activity. Thus, the behaviour of the enzyme in the swollen microgels is similar to the enzyme in solution, but the enzyme's activation energy increases when the water content in the microgels decreases. One important property of these biosensors is their remarkable stability. After 4 months of its manufacture, there is no loss in the initial response. Furthermore, the enzymatic activity of freeze-dried microgels containing enzyme remains unaltered for at least 18 months. 相似文献
44.
The UV photodissociation (<5 eV) of diiodomethane (CH(2)I(2)) is investigated by spin-orbit ab initio calculations. The experimentally observed photodissociation channels in the gas and condensed phases are clearly assigned by multi-state second-order multiconfigurational perturbation theory in conjunction with spin-orbit interaction through complete active space-state interaction potential energy curves. The calculated results indicate that the fast dissociations of the first two singlet states of CH(2)I(2) and CH(2)I--I lead to geminate-radical products, CH(2)I (.)+I((2)P(3/2)) or CH(2)I (.)+ I*((2)P(1/2)). The recombination process from CH(2)I--I to CH(2)I(2) is explained by an isomerization process and a secondary photodissociation reaction of CH(2)I--I. Finally, the study reveals that spin-orbits effects are significant in the quantitative analysis of the electronic spectrum of the CH(2)I--I species. 相似文献
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The Total Isomerization Process developed by Union Carbide in 1970 (Gary, 1987) for the conversion of normal paraffin's to their isomers consists of a reactor followed by a PSA unit each operating at similar pressures and temperatures. The combination of these two operations in one unit in a Pressure Swing Adsorption Reactor (PSAR) process may provide an increased throughput and a significant cost saving in ancillary equipment.The simulation of a mathematical model linking the catalyst packed-bed and the adsorbent packed-bed is reported. The catalyst is a Pd/Y-zeolite and the adsorbent is 5A zeolite. The simulated feed consists of 17% each of n- and isopentane with the remainder being hydrogen. The mathematical model assumes dispersed plug-flow in both sections, constant velocity in the reactor section but varying in the adsorber, with mass transfer in the adsorber section due to external fluid film resistance and macropore diffusion in series. The fraction of the total column length occupied by the catalyst (denoted by ) is accounted for in the model by solving numerically using orthogonal collocation on finite elements. Parameters varied are the ratio of catalyst/column length (), temperature range (506–533 K), high pressure (15–20 bars), with the low pressure held constant at 2 bars. The catalyst/column ratio has a strong effect at low temperatures. The optimum catalyst/column length ratio appears to be controlled by the low pressure step and occurs at = 0.7 for the assumptions used in this work. 相似文献
48.
Published information on methods for the production of benzazetines and their dehydro derivatives (benzazetes) and their chemical
transformations is reviewed and analyzed. It was noted that benzazetines with an unsubstituted NH group are unstable and their
stable representatives have only became accessible in recent years. The tendency of benzazetines to undergo opening of the
four-membered heterocycle and isomerization processes was demonstrated. The wide-ranging synthetic possibilities of benzazetines
and benzazetes are indicated.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1763–1783, December, 2007. 相似文献
49.
P. V. Bharatam Amita D. Kaur P. Senthil Kumar 《International journal of quantum chemistry》2006,106(5):1237-1249
The potential energy surface (PES) of thionylimide has been searched using ab initio MO and density functional calculations. The electronic structures of the isomers of HNSO have been studied using the HF/6‐31+G*, MP2(full)/6‐31+G*, and B3LYP/6‐31+G* levels. Final energies of these molecules have been calculated at the high‐accuracy G2 and CBS‐Q levels. The probable pathways of isomerization of thionylimide to its isomers (e.g., thiocyanic acid, HONS, nitrosothiols) have been explored by studying the three‐ or four‐membered transition states. This study identified total eight possible isomers ( 1–8 ) of HNSO, of which four ( 1–4 ) have already been realized experimentally. Of the remaining four ( 5–8 ), at least two ( 5, 7 ) can be generated experimentally. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 相似文献
50.
LBL分子沉积法制备葡萄糖氧化酶电极 总被引:1,自引:0,他引:1
采用以静电力为主的逐层分子交替沉积技术制备葡萄糖氧化酶(GOD)电极.通过带有正电荷的聚二甲基二烯丙基铵盐酸盐(PDDA)和带有负电荷的GOD交替沉积在修饰有3-巯基-1-丙基磺酸钠(MPS)的金电极表面.以甲酸二茂铁为电子媒介体,用循环伏安法检测GOD电极对葡萄糖的响应.结果表明,当GOD电极组装层数小于4时,电流响应随着层数的增加而增大,超过4层时电流响应减小.其中4层GOD修饰电极的线性范围为0.55~6.63 mmol•L-1,当pH为7.0时,响应最大.同时电极的检测重现性能良好,相对标准偏差为2.4%. 相似文献