环糊精对光催化制氢体系的影响

将环糊精应用于以铁氢化酶为催化剂,有机染料酸性红为光敏剂的均相制氢体系中,可提高铁氢化酶和光敏剂的水溶性和稳定性,从而提高了体系光催化制氢效率。在此光催化体系中所用催化剂铁氢化酶和光敏剂酸性红均不含有贵金属,除牺牲剂三乙胺外没有使用任何有机溶剂,为研究廉价和水溶性光催化制氢体系提供了新思路。     

二萜合酶标记底物的设计与合成

从二萜类天然产物Cyclooctatin的环化机理猜想出发,设计[2-2H]GGDP(GGDP:香叶基香叶基焦磷酸)、[9-2H2]GGDP、[14-2H]GGDP等氘代底物,以供研究二萜合酶环化反应机理,并设计[2-F]GGDP氟代底物用于与酶的共结晶研究,以验证猜想的正确性。均以反式-反式金合欢醇为起始原料,分别利用乙酰乙酸甲酯双负离子和单负离子偶联的方法实现碳链的延长,完成了[2-2H]GGDP和[2-F]GGDP的合成工作。在[2-2H]GGDP合成中,β-酮酸酯经D2O交换在C-2位引入氘原子;在[2-F]GGDP合成中,与乙酰乙酸甲酯单负离子偶联后经Krapcho脱羧反应和Horner-WadsworthEmmons反应在C-2位引入F原子。该研究为[9-2H2]GGDP、[14-2H]GGDP的合成积累了经验,也为后续进一步研究酶环化反应机制奠定了基础。     

四溴菊酸及其酯的合成与药效

本研究将二氯菊酸乙酯经过卤素的取代-加成反应而转变成四溴菊酸乙酯[Ⅰ]。并将四溴菊酸分别与3-苯氧基苄醇,N-羟甲基-3,4,5,6-四氢化邻苯二甲酰亚胺,α-氰基-3-苯氧基苄醇,4-甲氧甲基苄醇酯化,得到4种拟除虫菊酯[Ⅱ]、[Ⅲ]、[Ⅳ],[Ⅴ]。分别测定了它们对于孑孓、家蝇、蜚蠊的药效。其中[Ⅲ]、[Ⅴ]具有较强的杀虫活性。[Ⅴ]是尚未见报导的新拟除虫菊酯杀虫剂。     

含噻二唑杂环的1,8-萘酰亚胺衍生物的合成与表征

以4-溴-1,8-萘酐为起始原料,通过硝化、亲电取代、氢化还原、关环和亚酰化反应,合成了目标产物3,4-[1,2,3]-噻二唑-N-丙基-1,8-萘酰亚胺和3,4-[1,2,3]-噻二唑-N-丁基-1,8-萘酰亚胺.     

苯并[1,2,3]噻二唑-7-醛的合成

以2-氯-3,5-二硝基苯甲酸为起始原料,经过取代、酯化、还原重氮化等反应,合成了苯并[1,2,3]噻二唑-7-羧酸乙酯。并采用二异丁基氢化铝将其一步还原制备了苯并[1,2,3]噻二唑-7-醛。     

一些含噻唑杂环的萘酰亚胺衍生物的合成

以6-溴-1H,3H-苯并[de]吡喃-1,3-二酮为起始原料,通过硝化、氢化还原、关环和亚酰化反应,合成了3个含噻唑杂环的萘酰亚胺衍生物:N-丙基-9-苯基-苯并[de]噻唑[4,5-g]异喹啉-4,6-二酮、N-丁基-9-苯基-苯并[de]噻唑[4,5-g]异喹啉-4,6-二酮和N-羟乙基-9-苯基-苯并[de]噻唑[4,5-g]异喹啉-4,6-二酮.产物经过IR、1HNMR和元素分析进行了表征.     

新型人工氢化酶

人工酶研究的一项突破性进展可以帮助氢研究人员实现一个长期的目标:合成一类催化剂,利用其产生的H2可以为燃料电池提供能量、制备液体燃料和化学制品,以及应用于其他领域等。最近研制出的一种新型人工氢化酶,其效果与自然酶相当。当涉及到产生H2时,氢化酶是核心。但美中不足的是,只有代谢H2的细菌和藻类知道如何精确地合成氢     

氢化酶在生物技术中的应用

介绍了氢化酶的类型，讨论了氢化酶在生物制氢、废水处理、预防微生物腐蚀、NADP辅因子的产生及其再生等生物技术领域中的应用。随着基因组采集及筛选技术的提高很可能筛选出更新的氢化酶，应用于更广阔的领域。     

苄基脒类光产碱剂合成工艺研究

以1,5-二氮杂双环[4,3,0]-5-壬烯(DBN)为原料,采用氢化铝锂还原,于55℃下反应9 h,产物1,5-二氮杂双环[4,3,0]壬烷最高收率可达87.9%,纯度>95.0%;再将1,5-二氮杂双环[4,3,0]壬烷分别与不同取代苄基化合物反应,合成了系列新型标题化合物,并通过对其工艺条件的考察和优化,可使系列产物最高收率达89.9%,纯度>95.6%。研究中主要还运用了HPLC、LC-MS、1HNMR对产品及中间体进行了定量和定性分析。     

苯醚甲环唑和丙环唑对大型溞体内谷胱甘肽-S-转移酶(GST)活性影响

[目的]利用生物标志物作为农药毒性评价的研究受到日益广泛的重视,为了研究苯醚甲环唑和丙环唑对水生生物的毒性效应,寻找生物标志物。[方法]以48 h-EC50质量浓度0.52 mg/L处理48 h测定了大型溞体内GST酶活力与时间的效应关系以及不同浓度药剂处理48 h后GST酶活力与剂量的效应关系。[结果]不同时间处理时,随苯醚甲环唑和丙环唑处理时间的延长呈GST酶活性被诱导的幅度提高,处理48 h后酶活力达到最高值。不同质量浓度处理时,随苯醚甲环唑质量浓度的提高,GST酶活力诱导率增大,1.00 mg/L时诱导率最大,达到324.84%。[结论]试验结果表明GST酶可以作为苯醚甲环唑和丙环唑对大型溞毒性影响的生物标志物。     

“双碳”下金属纳米颗粒优化暗发酵制氢策略及前景

氢能是“双碳”下推动化石能源低碳转型的重要方向,微生物暗发酵制氢是实现生物质绿氢转化的有效途径。其中,利用具有量子尺寸效应、比表面积大和电导率高的金属纳米颗粒（MNPs）优化暗发酵制氢技术是近年研究热点。综述和评论了国内外添加MNPs用于优化暗发酵制氢性能的作用机制、技术难点和制氢效果等,重点阐述并比较了铁、镍和锌基三类热门MNPs优化策略在提高产氢酶系活性、增强代谢产氢途径和优化微生物群落结构等方面的作用,展望了暗发酵制氢可深入MNPs优化氢化酶活性、拓宽生物质发酵底物以及产氢菌筛选和反应器设计、生物质发酵技术开发等研究方向和应用前景。     

Hydrogenase-catalysed deposition of vivianite on mild steel

A simple device was designed with two mild steel electrodes placed face to face in the same phosphate solution and coupled through an external electrical circuit. A dialysis membrane retained hydrogenase from Ralstonia eutropha in contact with one electrode only. The simultaneous measurements of the electron flux in the electrical circuit and of nicotinamide adenine dinucleotide (NADH) production catalysed by hydrogenase proved that the enzyme induced the occurrence of cathodic and anodic micro-sites on the same electrode surface. A clear galvanic current was observed, which stopped after a few hours, because of the formation of a protective film of vivianite on the electrode that was in contact with hydrogenase. Hydrogenase in phosphate solution proved to be an effective trigger of mild steel corrosion. These results may be the basis of a new and easy-to-handle hydrogenase-catalysed phosphating process, which operates under mild conditions, avoids using toxic compounds, and is quite rapid.     

New hypotheses for hydrogenase implication in the corrosion of mild steel

The influence of [Fe]-hydrogenase from Clostridium acetobutylicum was studied on the anaerobic corrosion of mild steel. Two short-circuited mild steel electrodes were exposed to the same solution and hydrogenase was retained on the surface of only one electrode thanks to a dialysis membrane. The galvanic current and the electrode potential were measured as a function of time in order to monitor the difference in electrochemical behaviour induced by the presence of hydrogenase. A sharp potential decrease of around 500 mV was controlled by the deoxygenating phase. When hydrogenase was introduced after complete deoxygenation, significant heterogeneous corrosion was observed under the vivianite deposit on the electrode in contact with hydrogenase, while the other electrode only showed the vivianite deposit, which was analysed by MEB and EDX. The effect of hydrogenase was then confirmed by monitoring the free potential of single coupons exposed or not to the enzyme in a classical cell after complete deoxygenating. In both phosphate and Tris-HCl buffers, the presence of hydrogenase increased the free potential around 60 mV and induced marked general corrosion. It was concluded that [Fe]-hydrogenase acts in the absence of any final electron acceptor by catalysing direct proton reduction on the mild steel surface.     

Designed Surface Residue Substitutions in [NiFe] Hydrogenase that Improve Electron Transfer Characteristics

Photobiological hydrogen production is an attractive, carbon-neutral means to convert solar energy to hydrogen. We build on previous research improving the Alteromonas macleodii “Deep Ecotype” [NiFe] hydrogenase, and report progress towards creating an artificial electron transfer pathway to supply the hydrogenase with electrons necessary for hydrogen production. Ferredoxin is the first soluble electron transfer mediator to receive high-energy electrons from photosystem I, and bears an electron with sufficient potential to efficiently reduce protons. Thus, we engineered a hydrogenase-ferredoxin fusion that also contained several other modifications. In addition to the C-terminal ferredoxin fusion, we truncated the C-terminus of the hydrogenase small subunit, identified as the available terminus closer to the electron transfer region. We also neutralized an anionic patch surrounding the interface Fe-S cluster to improve transfer kinetics with the negatively charged ferredoxin. Initial screening showed the enzyme tolerated both truncation and charge neutralization on the small subunit ferredoxin-binding face. While the enzyme activity was relatively unchanged using the substrate methyl viologen, we observed a marked improvement from both the ferredoxin fusion and surface modification using only dithionite as an electron donor. Combining ferredoxin fusion and surface charge modification showed progressively improved activity in an in vitro assay with purified enzyme.     

A membrane-bound cytochrome c3: a type II cytochrome c3 from Desulfovibrio vulgaris Hildenborough

A new tetraheme cytochrome c3 was isolated from the membranes of Desulfovibrio vulgaris Hildenborough (DvH). This cytochrome has a molecular mass of 13.4 kDa and a pI of 5.5 and contains four heme c groups with apparent reduction potentials of -170 mV, -235 mV, -260 mV and -325 mV at pH 7.6. The complete sequence of the new cytochrome, retrieved from the preliminary data of the DvH genome, shows that this cytochrome is homologous to the "acidic" cytochrome c3 from Desulfovibrio africanus (Da). A model for the structure of the DvH cytochrome was built based on the structure of the Da cytochrome. Both cytochromes share structural features that distinguish them from other cytochrome c3 proteins, such as a solvent-exposed heme 1 surrounded by an acidic surface area, and a heme 4 which lacks most of the surface lysine patch proposed to be the site of hydrogenase interaction in other cytochrome c3 proteins. Furthermore, in contrast to previously discovered cytochrome c3 proteins, the genes coding for these two cytochromes are adjacent to genes coding for two membrane-associated FeS proteins, which indicates that they may be part of membrane-bound oxidoreductase complexes. Altogether these observations suggest that the DvH and Da cytochromes are a new type of cytochrome c3 proteins (Type II: TpII-c3) with different redox partners and physiological function than the other cytochrome c3 proteins (Type I: TpI-c3). The DvH TpII-c3 is reduced at considerable rates by the two membrane-bound [NiFe] and [NiFeSe] hydrogenases, but catalytic amounts of TpI-c3 increase these rates two- and fourfold, respectively. With the periplasmic [Fe] hydrogenase TpII-c3 is reduced much slower than TpI-c3, and no catalytic effect of TpI-c3 is observed.     

Immobilization of Desulfovibrio vulgaris cells with hydrogenase activity

Desulfovibrio vulgaris intact cells immobilized in calcium alginate retained 45% of the hydrogenase activity of free cells. Cell immobilization had no effect on the optimum temperature for the hydrogen uptake rate, whereas the pH optimum was shifted to a higher value. The immobilization conferred on the cells a protection both against oxygen inhibition and thermal denaturation of the hydrogenase system.     

Electrically conducting particle networks in polymer electrolyte as three-dimensional electrodes for hydrogenase electrocatalysis

Efficient H₂ oxidation and production by hydrogenase enzymes has attracted much interest because of the possibilities it raises for clean energy cycling without the need for precious metal catalysts. Although hydrogenases are extremely active electrocatalysts, high surface-area electrode structures will be necessary if the enzymes are to find application in energy technologies. Taking inspiration from fuel cell electrode assemblies, in which metal nanoparticles are commonly mounted on particulate carbon supports encased in polymer electrolyte, we show that high surface-area hydrogenase electrodes can be constructed from enzyme-loaded pyrolytic graphite particles in pH-neutralised Nafion. Pyrolytic graphite is the favoured surface for direct electrochemistry of many redox proteins, and on sanding, yields micron-dimension platelike particles. By modifying graphite platelets with hydrogenase before assembling the particles into a network, we ensure a high, uniform enzyme coverage. Incorporation of hydrogenases into high surface-area conducting network electrodes enhanced electrocatalytic H₂ oxidation currents by 30-times compared to values obtained for a planar hydrogenase electrode, while retaining efficient conductivity and H₂ mass transport through the network. This approach should make it possible to directly compare enzyme and precious metal electrocatalysis and to benchmark what opportunities are possible with selective enzyme catalysts.     

PRODUCTION OF ACETIC ACID FROM HYDROGEN AND CARBON DIOXIDE BY CLOSTRIDIUM SPECIES ATCC 29797

Clostridium sp. ATCC 29797 converts H₂ and CO₂ to acetic acid in stationary phase in almost 100% yield. The resting cells are stable for up to 300 h and produce acetate to a final product concentration of 221 mM. The specific productivity of acetate during the stationary phase appears limited by the specific activity of hydrogenase. A high pressure fermentor was constructed to investigate the use of pressure, as a general strategy, for increasing the rates of microbial syngas conversions. Fermentations were conducted at pressures up to 1000 psig using various mixtures of H₂ and CO₂. The use of high pressure proved to be an effective method for eliminating gas transfer resistances and increasing the volumetric productivity. Hydrostatic pressure had little effect on the specific productivity of acetate, however, high partial pressures of hydrogen caused the specific productivity and total acetate accumulated to decrease. High pressures of hydrogen also caused a decrease in the specific activity of hydrogenase. These results suggest that Clostridium sp. ATCC 29797 attempts to control the input of reducing power by regulating the activity of hydrogenase.     

PRODUCTION OF ACETIC ACID FROM HYDROGEN AND CARBON DIOXIDE BY CLOSTRIDIUM SPECIES ATCC 29797

Clostridium sp. ATCC 29797 converts H₂ and CO₂ to acetic acid in stationary phase in almost 100% yield. The resting cells are stable for up to 300 h and produce acetate to a final product concentration of 221 mM. The specific productivity of acetate during the stationary phase appears limited by the specific activity of hydrogenase. A high pressure fermentor was constructed to investigate the use of pressure, as a general strategy, for increasing the rates of microbial syngas conversions. Fermentations were conducted at pressures up to 1000 psig using various mixtures of H₂ and CO₂. The use of high pressure proved to be an effective method for eliminating gas transfer resistances and increasing the volumetric productivity. Hydrostatic pressure had little effect on the specific productivity of acetate, however, high partial pressures of hydrogen caused the specific productivity and total acetate accumulated to decrease. High pressures of hydrogen also caused a decrease in the specific activity of hydrogenase. These results suggest that Clostridium sp. ATCC 29797 attempts to control the input of reducing power by regulating the activity of hydrogenase.     

苯并-15-冠-5-修饰的ADT型铁氢化酶活性中心模型的电催化产氢行为

利用Sonogashira反应,以较高的产率将苯并-15-冠-5-基团修饰到铁氢化酶活性中心,得到了结构新颖的ADT型模型化合物1,电化学研究表明该化合物能够催化还原醋酸放出氢气,具有明显的产氢活性.