Synthesis,characterization and catalytic reactivity of pentacoordinate iron dicarbonyl as a model of the [Fe]-hydrogenase active site

Two mono iron complexes Fe（CO）2PR3（NN） （R = Cy （3）, Ph （4）, NN = o-phenylenediamine dianion ligand, N2H2Ph2-） derived from the ligand substitution of Fe（CO）3hPR3 by the NN ligand were isolated and structurally characterized by single crystal X-ray diffraction. They have a similar first coordination sphere and oxidation state of the iron center as the [Fe]-hydrogenase active site, and can be a model of it IR demonstrated that the effect of the NN ligand on the coordinated CO stretch- ing frequencies was due to its excellent electron donating ability. The reversible protonation/deprotonation of the NN ligand was identified by infrared spectroscopy and density functional theory computation. The NN ligand is an effective proton acceptor as the internal base of the cysteine thiolate ligand in [Fe]-hydrogenase. The electrochemical properties of complexes 3, 4 were investigated by cyclic voltammograms. Complex 3 catalyzed the transfer hydrogenation of benzoquinone to hydroquinone effectively under mild conditions.

Polymorphisms of alcohol dehydrogenase 2 and aldehyde dehydrogenase 2 and colorectal cancer risk in Chinese males

AIM: To evaluate the relationship between drinking and polymorphisms of alcohol dehydrogenase 2 (ADH2) and/or aldehyde dehydrogenase 2 (ALDH2) for risk of colorectal cancer (CRC) in Chinese males. METHODS: A case-control study was conducted in 190 cases and 223 population-based controls. ADH2 Arg47His (G-A) and ALDH2 Glu487Lys (G-A)genotypes were identified by PCR and denaturing high-performance liquid chromatography (DHPLC). Information on smoking and drinking was collected and odds ratio (OR) was estimated. RESULTS: The ADH2 A/A and ALDH2 G/G genotypes showed moderately increased CRC risk. The age- and smoking-adjusted OR for ADH2 A/A relative to G/A and G/G was 1.60 (95% CI=1.08-2.36), and the adjusted OR for ALDH2 G/G relative to G/A and A/A was 1.79 (95% CI=1.19-2.69). Signif icant interactions between ADH2, ALDH2 and drinking were observed. As compared to the subjects with ADH2 G and ALDH2 A alleles, those with ADH2 A/A and ALDH2 G/G genotypes had a signif icantly increased OR (3.05, 95% CI= 1.67-5.57). The OR for CRC among drinkers with the ADH2 A/A genotype was increased to 3.44 (95% CI= 1.84-6.42) compared with non-drinkers with the ADH2 G allele. The OR for CRC among drinkers with the ALDH2 G/G genotype was also increased to 2.70 (95% CI= 1.57-4.66) compared with non-drinkers with the ALDH2 A allele. CONCLUSION: Polymorphisms of the ADH2 and ALDH2 genes are significantly associated with CRC risk. There are also signifi cant gene-gene and gene- environment interactions between drinking and ADH2 and ALDH2 polymorphisms regarding CRC risk in Chinese males.

ISOLATION, PURIFICATION AND CHARACTERIZATION OF THE HYDROGEN EVOLUTION PROMOTING FACTOR OF HYDROGENASE OF SPIRULINA PLATENSIS

A component （s-factor） with obvious promoting effect on hydrogen evolution of hydrogenase has beenisolated and extracted from a Cell=free preparation of Spirulina platensis.The effect of the s-factor in the re-action system is similar to that of Na2S2O4, but is coupled with ligh. The s-factor has the maximumabsorption peak at 620 nm in the oxidized state, at 590 nm in the reduced state. The partially purifieds-factor showed two bands by SDS-PAGE and is distinctly different from phycocyanin,which has nochange of oxidized state and reduced state absorption spectra, and also has no promoting effect onhydrogenase of Spirulina platensis under the light.

Photoinduced hydrogen evolution in an artificial system containing photosystem I, hydrogenase, methy1 viologen and mercaptoacetic acid

Hydrogen evolution was detected in an artificial system composed of light-harvesting unit of purified photosystem I, catalyst of hydrogenase, methyl viologen and electron donor under radiation. Absorption spectral features confirmed that electron transfer from electron donors to proton was via a photoinduced reductive process of methyl viologen.

Optimization of detecting hydrogenase activity for acidogenic fermentation of activated sludge

In order to evaluate the hydrogen-producing efficiency of anaerobic activated sludge in Anaerobic Baffled Reactor(ABR)fermentation processes,the optimal conditions for hydrogen producing hydrogenase method on methyl viologen(MV)assay was used to detect the hydrogen production activity of the activated sludge.The most favorable parameters such as 0.6 mL sodium acetate buffer(pH 5.0),100 μL lysozyme,0.2 mL sodium dibromoethane(9.0 mmol/L)and 0.7 mmol/L iron added into 1 mL activated sludge(2.66～26.64 gMLVSS/L)were found.Furthermore,reaction temperature and culture time were detected as 40 ℃ and 30 min respectively.Sodium thiosulfate and sodium sulfides were taken as the reducing agent while trichloroacetic acid as terminator.Under the MV optimal conditions,micro-toxic Dimethyl sulfoxide(DMSO)get higher security and better accuracy.The sensitivity of the detection methods(DMSO as electron carrier)was increased by more than 30%.The results show that the optimal conditions can be applied to measure hydrogenase activity correlating with its specific hydrogen production rate in a hydrogen-producing anaerobic activated sludge system.

Synthesis and Crystal Structure of a Model for the Active Sites of Fe-only Hydrogenases:[Fe_2(SCH_2)_2N(3-PhCF_3)(CO)_6]_2

A model compound for the active sites of Fe-only hydrogenases, [Fe2（SCH2）2N（3- PhCF3）（CO）6]2, has been synthesized and structurally characterized by single-crystal X-ray diffraction. It crystallizes in tetragonal, space group P43, with α = 12.6324（3）, b = 12.6324（3）, c = 24.0453（12） A, V = 3837.1（2） A^3, Z= 4, Fe4S4N2C30O12F6H16, Mr= 1062.09, Dc= 1.839 g/cm^3, μ（MoKα） = 1.791 mm^-1, F（000） = 2112, T= 293（2） K, Flack = 0.034（9）, R = 0.0282 and wR = 0.0685 for 8148 observed reflections with I 〉 20（I）. In the title compound, each Fet atom is coordinated by three terminal carbonyl C atoms （Fe-C： 1.783（3）- 1.816（3） A）, two bridging S atoms （Fe-S： 2.2609（7）-2.2757（8） A） and another Fe atom （Fe-Fe 2.5011（5） A）, adopting a distorted octahedral geometry with trans angles ranging from 152.45（11） to 157.77（10）°.

Comparative evaluation of different cell disruption methods for the release of hydrogenase from H2 -producing bacterium E. harbinenase YUAN-3T

A comparative evaluation of three different cell-disruption methods for the release of hydrogenase from H2 -producing bacterium E. harbinenase YUAN-3T was investigated. The cell disruption techniques evaluated in this study were uhrasonieation, high-speed homogenization and bead milling. Ultrasonication process was found to be the most effective method in terms of cell disruption. As for the specific activity of hydrogenase, there is no significant difference among the three kinds of methods. An orthogonal experiment L9 （34） was designed to optimize the procedures of ultrasonication for cell disruption. The optimized uhrasonication disruption conditions were the treatment at 250 W, 20 kHz, 30 s/15 s and 0. 30 g bacteria cell （dry weight） in 15 mL suspension buffer. As a result, the optimized conditions allow the hydrogenase to maintain the active form with the yield of 93.95 mg protein/g cell and the final activity of 0. 252 μmol/min/mg protein. In this work, we have developed and optimized an ultrasonication protocol for YUAN-3T cel]s, which is adapted to laboratory- scale release of hydrogenase proteins.

Selective photocatalytic reduction of CO2 to CO mediated by a[FeFe]-hydrogenase model with a 1,2-phenylene S-to-S bridge

Photocatalytic reduction of CO2 to CO is a promising approach for storing solar energy in chemicals and mitigating the greenhouse effect of CO2.Our recent studies revealed that[(μ-bdt)Fe2(CO)6](1,bdt=benzene-1,2-dithiolato),a[FeFe]-hydrogenase model with a rigid and conjugate S-to-S bridge,was catalytically active for the selective photochemical reduction of CO2 to CO,while its analogous complex[(μ-edt)Fe2(CO)6](2,edt=ethane-1,2-dithiolato)was inactive.In this study,it was found that the turnover number of 1 for CO evolution reached 710 for the 1/[Ru(bpy)3]2+/BIH(BIH=1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]-imidazole)system under optimal conditions over 4.5 h of visible-light irradiation,with a turnover frequency of 7.12 min−1 in the first hour,a high selectivity of 97%for CO,and an internal quantum yield of 2.8%.Interestingly,the catalytic selectivity of 1 can be adjusted and even completely switched in a facile manner between the photochemical reductions of CO2 to CO and of protons to H2 simply by adding different amounts of triethanolamine to the catalytic system.The electron transfer in the photocatalytic system was studied by steady-state fluorescence and transient absorption spectroscopy,and a plausible mechanism for the photocatalytic reaction was proposed.

Five-heterocyclic-biphosphine-substituted Fe-only Hydrogenase Mimic： Synthesis,Characterization and Properties

A new five-heterocyclic-biphosphine-substituted Fe-only hydrogenase mimic,[（μ-pdt）Fe_2（CO）_5]_2（PTP）（1）,has been synthesized at room temperature. 1·H_2O crystallizes in triclinic system,space group P1,with a = 11.5897（4）,b = 13.6156（4）,c = 18.0333（6） ？,α = 76.306（3）,β = 72.742（3）,γ = 68.939（3）°,V = 2508.84（14） ？~3,Dc = 1.570 g/cm3,Z = 2,M_r = 1186.37,F（000） = 1204,the final R = 0.0748,and wR = 0.2012. In the tetranuclear complex 1·H_2O,each [2Fe_2S] butterfly unit is attached to one P atom of the diphosphine bridge and exhibits a square-pyramidal geometry. Complex 1 was characterized by elemental analysis,IR spectra,UV-vis absorption spectra,~1H-NMR and ^（31）P-NMR. The cyclic voltammetry behavior of compound 1 was investigated as well.

Hydrogenase as the basis for green hydrogen production and utilization

Hydrogenase is a paradigm of highly efficient biocatalyst for H_(2) production and utilization evolved in nature. A dilemma is that despite the high activity and efficiency expected for hydrogenases as promising catalysts for the hydrogen economy, the poor oxygen tolerance and low yield of hydrogenases largely hinder their practical application. In these years, the enigmas surrounding hydrogenases regarding their structures, oxygen tolerance, mechanisms for catalysis, redox intermediates, and proton-coupled electron transfer schemes have been gradually elucidated;the schemes, which can well couple hydrogenases with other highly efficient(in)organic and biological catalysts to build novel reactors and drive valuable reactions, make it possible for hydrogenases to find their niches. To see how scientists put efforts to tackle this issue and design novel reactors in the fields where hydrogenases play crucial roles, in this review,recent advances were summarized, including different strategies for protecting enzyme molecules from oxygen, enzyme-based assembling systems for H_(2) evolution in the photoelectronic catalysis, enzymatic biofuel cells for H_(2) utilization and storage and the efficient electricity-hydrogen-carbohydrate cycle for high-purity hydrogen and biofuel automobiles. Limitations and future perspectives of hydrogenasebased applications in H_(2) production and utilization with great impact are discussed. In addition, this review also provides a new perspective on the use of biohydrogen in healthcare beyond energy.

Bacterial UDP-Glucose Hydrolases and P2 Receptor-Mediated Responses to Infection: A Commentary

UDP-glucose hydrolases are a group of relatively little known membrane-bound or periplasmic enzymes found in Salmonella enterica and E. coli. UDP-glucose is an agonist for a specific P2 receptor (P2Y14) found on epithelial cells and cells associated with innate immunity. It is also recognised as a ‘danger signal’. Cells respond to mechanical damage by releasing UDP-glucose which activates P2Y14 to trigger an innate immune response;it is postulated that a similar response to bacterial infection may be protective against infection. However, the UDP-glucose hydrolases may constitute virulence factors able to abrogate this response by degradation of the released UDP-glucose.

A New Pyridine-substituted Azadithiolate 2Fe2S Complex Related to the Active Site of[FeFe]-hydrogenase

A new 2Fe2 S complex[（2-C5H4N）N（μ-CH2S）2Fe2（CO）6]（1） related to the active site of[FeFe]-hydrogenase was obtained by treating（HS）2Fe2（CO）6 with（pyridin-2-ylazanediyl）dimethanol.Protonation occurred at the pyridine nitrogen atom when two equivalents of HBF4·OEt2acid were added to the toluene solution of 1,leading to the formation of[（2-C5H4NH）N（μ-CH2S）2Fe2（CO）6]·BF4·OEt2（1H~＋）,whose molecular structure was further established by singlecrystal X-ray analysis.Complex 1 crystallizes in the monoclinic system,space group P21/n with α=7.728（3）,b = 11.825（4）,c = 17.888（6） A,β= 92.968（5）°,while complex 1H~＋ crystallizes in the triclinic system,space group P1 with a = 7.672（4）,b = 10.382（5）,c = 16.480（10） A,α=106.575（13）,β= 93.18（3）,γ=104.262（17）°.

浮动海上有机农场——Hydrogenase

浮动有机农场Hydrogenase外形看起来如同丝网编织的精美花边,是一个真正的净化站.位于4个碳回收塔内的绿色海藻将回收船舶带来的碳废物,可以直接用于这座"飞艇"形的有机农场的生物制氢,相当于传统飞机跑道边的加油站.

绿藻产氢的机制及研究进展

系统介绍绿藻在厌氧条件下利用氢化酶产氢的3种不同途径,包括依赖光系统II的直接产氢、不依赖光系统II的间接产氢和暗发酵产氢,同时分析3种产氢途径各自的优缺点。受技术和制造成本限制,绿藻产氢仍处于初步开发阶段,实现大规模工业生产仍需很长一段时间。针对提高绿藻产氢效率、实现工业化的目标,综述该领域最新研究结果,概括从氢化酶改造、降低体系中氧气含量、减弱环式电子传递、降低卡尔文循环、缩小捕光天线、底物预处理和光生物反应器设计等7个方向优化产氢反应的方式,并展望绿藻产氢的未来发展趋势。

氢气代谢及其环境生物修复功能研究进展

分子氢是多种微生物代谢之间相互作用的关键中介物,环境中产氢微生物和耗氢微生物的活动决定了全球氢气循环,对其他重要元素生物地球化学循环具有潜在的驱动作用。环境功能微生物在维持环境生态系统平衡、消除次生环境污染等领域中扮演着不容忽视的重要作用。因此,理解环境中氢气代谢(氢气的产生和消耗)微生物对生态环境的影响及其在环境生物修复中的作用与功能,对认识氢气的生态环境效应并将该生物能源应用于生物修复具有重要的科学意义和实践价值。系统分析了氢气代谢过程及氢化酶的分类和功能,总结了微生物产生和消耗氢气的多种途径及其对土壤生态环境效应和生物修复作用的影响,指出了目前氢气代谢过程及氢化酶应用于环境生物修复领域存在的关键科学技术问题,提出了未来的研究思路与重点方向,以推动氢气这种生物能源成就一种有前景的环境污染修复策略。

CAR、FAR、LDH、D-二聚体对间质性肺病合并病毒感染严重程度的预测价值

目的 评估C-反应蛋白/白蛋白比值(CAR)、纤维蛋白原/白蛋白比值(FAR)、乳酸脱氢酶(LDH)、D-二聚体对间质性肺病(ILD)合并病毒感染严重程度的预测价值。方法 选取2019年6月-2022年12月在承德医学院附属医院临床诊断为间质性肺病(ILD),病毒血清学IgM抗体阳性的49例患者为病例组并随机选取病毒血清学IgM阴性54例患者作为对照组,收集并分析它们的临床资料,实验室检查结果。结果 49例患者中最常见的单一病毒感染是乙型流感病毒,混合感染是甲型流感病毒+腺病毒+呼吸道合胞病毒;感染患者年龄较对照组大(P<0.05),咳嗽、咳痰、呼吸困难的比率较对照组高(P<0.05);感染患者CAR、FAR、LDH、D-二聚体、血沉(ESR)、C-反应蛋白(CRP)、纤维蛋白原(FIB)、纤维蛋白原降解产物(FDP)高于对照组(P<0.05),治疗好转率、氧合指数、白蛋白(ALB)较对照组低(P<0.05);CAR、FAR、LDH、D-二聚体与炎症因子ESR、CRP呈正相关(P<0.05);与氧合指数呈负相关(P<0.05),ROC曲线显示联合四项指标有较高的曲线下面积(AUC=0.791),联合指标的AUC大于CAR(Z=2.323,P=0.020)、FAR(Z=2.062,P=0.039),但与D-二聚体(Z=1.876,P=0.061)、LDH(Z=1.182,P=0.237)差异无统计学意义。结论 感染患者CAR、FAR、LDH、D-二聚体明显升高,炎症反应剧烈,治疗效果不佳。

A functional hydrogenase mimic that catalyzes robust H_(2) evolution spontaneously in aqueous environment

Although great progress has been made in improving hydrogen production,highly efficient catalysts,which are able to produce hydrogen in a fast and steady way at ambient temperature and pressure,are still in large demand.Here,we report a[NiCo]-based hydrogenase mimic,NiCo_(2)O_(4) nanozyme,that can catalyze robust hydrogen evolution spontaneously in water without external energy input at room temperature.This hydrogenase nanozyme facilitates water splitting reaction by forming a three-center Ni-OH-Co bond analogous to the[NiFe]-hydrogenase reaction by using aluminum as electron donor,and realizes hydrogen evolution with a high production rate of 915 L·h^(-1) per gram of nanozymes,which is hundreds of times higher than most of the natural hydrogenase or hydrogenase mimics.Furthermore,the NiCo_(2)O_(4) nanozyme can robustly disrupt the adhesive oxidized layer of aluminum and enable the full consumption of electrons from aluminum.In contrast to the often-expensive synthetic catalysts that rely on rare elements and consume high energy,we envision that this NiCo_(2)O_(4) nanozyme can potentially provide an upgrade for current hydrogen evolution,accelerate the development of scale-up hydrogen production,and generate a clean energy future.

氢化酶固定化研究进展

氢化酶催化氢气向质子和电子的可逆转化,具有广阔的工业应用前景。但游离的氢化酶存在着对氧气敏感、传递电子速率慢等缺点。本文综述了碳材料、金属及半导体、高分子和金属-有机框架材料(MOF)固定化氢化酶。碳材料具有价格低廉、比表面积大等优势。金属及半导体有着良好的导电性能和优异的催化性能。高分子材料具有良好的生物相容性和机械性能,可以提高氢化酶的稳定性和对氧气的耐受性。MOF比表面积大,可设计调控,为理化性质不同的氢化酶提供了广泛的载体选择。复合材料固定化氢化酶可以结合不同材料的优势,拓宽固定化氢化酶的应用场景。固定化氢化酶可用于氢气的高效生产与应用以及生物不对称加氢制备手性化合物,为转变能源结构、实现绿色转型、解决环境问题提供了可选方案。

体外多酶分子机器产氢应用中的氢酶研究

氢酶是生物制氢和氢能利用的最关键酶,它是一类广泛分布的对氧敏感的多亚基金属复合酶。体外多酶分子机器是体外生物转化技术中的高效酶生物催化系统,利用该分子机器生产氢气是一种新型高效的绿氢生产技术,它突破微生物产氢的Thauer极限,将葡萄糖产氢的转化率提高至接近化学理论值(1 mol葡萄糖裂解水生产12 mol氢气),代表着生物产氢的未来方向。氢酶的制备及催化性能是限制多酶分子机器产氢技术广泛应用的主要瓶颈;氧气不仅抑制氢酶的活性,也是氢酶转录翻译及翻译后加工的重要影响因素。体外多酶分子机器对氢酶的耐氧性能、热稳定性及高周转性能等参数提出高要求。本文结合氢酶在多酶分子机器制氢应用中的技术障碍,针对迫切的基础科学问题,分别从氢酶分类、结构功能、重组表达技术进展、(仿生)辅酶的适配等方面对其进行了相关的总结,并初步对氧的抑制机制、微生物重组表达氢酶以及产氢人工电子传递链的优化等难点问题的研究进行了跟踪,期待能够为氢酶在体外合成生物学的应用提供参考。

[NiFe]-氢化酶仿生化学模拟合成研究进展

介绍了氢化酶家族中重要的成员之一[NiFe]-氢化酶的活性中心结构和催化机理。综述了[NiFe]-氢化酶的双金属活性中心结构仿生化学模拟合成研究工作,一些具有代表性的[NiFe]-氢化酶模型物的合成方法和结构信息进行了描述。分析了近期研究者对[NiFe]-氢化酶仿生化学模拟合成研究的方向与重点,以及在[NiFe]-氢化酶仿生化学模拟合成工作上取得的一些成果,最后展望了[NiFe]-氢化酶模型物的未来发展前景与意义,为[NiFe]-氢化酶仿生化学研究提供参考。