Lewis酸催化Glyoxylate-Ene反应合成α-羟基酯的研究

研究比较了几种Lewis酸对α-甲基苯乙烯和乙醛酸乙酯反应合成α-羟基-4-苯基-4-戊烯酸乙酯(EHPP)的催化性能,其中SnCl4的催化活性最高。在n(α-甲基苯乙烯)∶n(乙醛酸乙酯)∶n(SnCl4)=1∶1∶0.03,反应温度20℃,反应时间90 min的条件下,α-甲基苯乙烯的转化率为98.6%,EHPP的选择性和收率分别达到95.6%和94.3%。同时研究了其他烯烃和乙醛酸酯合成α-羟基酯的反应,结果表明SnCl4也具有较高的催化活性。

Conversion of acetate and glyoxylate to fumarate by a cell-free synthetic enzymatic biosystem

Fumarate is a value-added chemical that is widely used in food,medicine,material,and agriculture industries.With the rising attention to the demand for fumarate and sustainable development,many novel alternative ways that can replace the traditional petrochemical routes emerged.The in vitro cell-free multi-enzyme catalysis is an effective method to produce high value chemicals.In this study,a multi-enzyme catalytic pathway comprising three enzymes for fumarate production from low-cost substrates acetate and glyoxylate was designed.The acetyl-CoA synthase,malate synthase,and fumarase from Escherichia coli were selected and the coenzyme A achieved recyclable.The enzymatic properties and optimization of reaction system were investigated,reaching a fumarate yield of 0.34 mM with a conversion rate of 34%after 20 h of reaction.We proposed and realized the conversion of acetate and glyoxylate to fumarate in vitro using a cell-free multi-enzyme catalytic system,thus providing an alternative approach for the production of fumarate.

Fatty acid feedstocks enable a highly efficient glyoxylate-TCA cycle for high-yield production of β-alanine

Metabolic engineering to produce tricarboxylic acid(TCA)cycle-derived chemicals is usually associated with problems of low production yield and impaired cellular metabolism.In this work,we found that fatty acid(FA)feedstocks could enable high-yield production of TCA cycle-derived chemicals,while maintaining an efficient and balanced metabolic flux of the glyoxylate-TCA cycle,which is favorable for both product synthesis and cell growth.Here,we designed a novel synthetic pathway for production of β-alanine,an important TCA cycle-derived product,from FAs with a high theortecial yield of 1.391 g/g.By introducing panD,improving aspA,and knocking out iclR,glyoxylate shunt was highly activated in FAs and the yield of β-alanine reached 0.71 g/g from FAs,much higher than from glucose.Blocking the TCA cycle at icd/sucA/fumAC nodes could increase β-alanine yield in a flask cultivation,but severely reduced cell growth and FA utilization during fed-batch processes.Replenishing oxaloacetate by knocking out aspC and recovering fumAC could restore the growth and lead to a titer of 35.57 g/l.After relieving the oxidative stress caused by FA metabolism,β-alanine production could reach 72.05 g/l with a maximum yield of 1.24 g/g,about 86% of the theoretical yield.Our study thus provides a promising strategy for the production of TCA cycle-derived chemicals.

Study on Lewis acid promoted condensation of allylalkoxysilanes with (-)-menthyl glyoxylate

Allylalkoxydimethylsilanes (2) condense with (-)-menthyl glyoxylate (3) in the presence of Lewis acid to give optically active menthyl 2-hydroxy-4-pentenoate (7) with optical purity of 31-42%. Factors affecting the yield and de of 7 have been examined. The stereochemistry of transition state of the reaction was discussed.

Enhancement of the Essential Amino Acid Composition of Food Crop Proteins through Biotechnology

Lack of essential amino acids (EAA) in the diet of at-risk populations could beget a state of food insecurity. Plant proteins are deficient in some essential amino acids. Animals obtain EAA from plant sources. Simple biotechnologies are being developed for improving the EAA composition of crop proteins. The aim was to integrate-discriminate glycolysis and citric-glyoxylic acid cycles to optimize biosynthesis of EAA in food crops. Permutation of diverse metabolic pathways at the mRNA level by glutamate dehydrogenase (GDH)-synthesized RNA is a common biotechnology for doubling the nutritious compositions of plants. Peanuts were planted in plots and treated with mineral salts mixed according to stoichiometric ratios. Protein-bounded and free amino acids of mature peanut seeds were determined by HPLC. GDH-synthesized RNA probes homologous to the mRNAs encoding glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoglycerate mutase (PGlycM), phosphoenolpyruvate carboxylase (PEPCase), enolase, malate dehydrogenase (MDH), isocitrate lyase (ICL), and malate synthase (MS) were prepared from peanut seeds using restriction fragment double differential display PCR method. Northern assays of peanut total RNA showed that the mRNAs encoding PGlycM, PEPCase, MDH, and MS shared extensive sequence homologies that produced a dense network of cross-talks, resulting to co-differential silencing of the mRNAs thereby permuting glycolysis, citric-glyoxylic acid cycles. There were 42 permutations in the NPPKtreated, 105 in control, 420 in KN-, and NPKS-treated peanuts. Because of permutations involving the mRNAs encoding ICL and MS, wherever the abundances of these mRNAs were high (control, and NPPK-treated peanuts) the concentrations of the α-ketoglutarate group of total glutamate, glutamine, arginine, proline, and histidine were minimized (<7.0 mg/g) but the concentrations of the oxaloacetate group of total aspartate, lysine, methionine, threonine, and isoleucine were maximized (>28.0 mg/g). The integration of glycolysis, citric and glyoxylic acid cycles increased the quality and doubled the concentrations of the protein-bounded EAA composition of NPPK-treated (33.37 mg/g) compared with the control peanut (15.66 mg/g). The commanding biotechnology was the stoichiometric mineral salts-based induction of GDH to synthesize the RNAs that integrated glycolysis, citric-glyoxylic acid cycles to one functional unit.

The Strengths, Weaknesses, Opportunities and Threats (SWOT) Analysis of <i>Mycobacterium tuberculosis</i>: A Systematic Review

Background: Mycobacterium tuberculosis, the etiology of pulmonary and extra pulmonary tuberculosis is taunted to have predated the existence of mankind, and science has elucidated its presence in old Egyptian’ mummies, as it continues to evade current antibiotic treatments, wreck the havoc and decimate human populations. Presented here, are the Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis of Mycobacterium tuberculosis, and the first proposal for the application of this innovative concept in the field of Tuberculosis research, to proffer holistic platform, focused knowledge, and strategies at undermining the prowess of the tubercle bacilli and overcoming its scourge. Materials and Methods: A systematic review was carried out to mine data on the strengths, the weaknesses, the opportunities and threats to M. tb, by review of several publications using meaningful theme and specific search phrases on the subject. Results: Strengths of Mycobacterium tuberculosis include: possession of abundant cell wall mycothiol;M. tb is highly contagious and requires low infectious dose (ID50) to establish infection;ability to specifically target and replicate in the host’ macrophages;ability to establish extrapulmonary multiorgan involvement;dual polymorphism i.e. existence in both an actively replicating form as well as or latent state;assumption of variable metabolic states;delayed seeding from the lungs of the replicating bacteria cells to the mediastinal lymph nodes;delayed macrophage apoptosis prior to bacterial growth and ultimate cellular necrosis;ability to shift to glyoxylate pathway during lipid metabolism in lieu of glucose during persistence phase in the host. Weaknesses of M. tuberculosis include: the requirement for growth of a membrane protein called Rv3671c during in vivo replication for survival in the acidic milieu of the macrophages and phagosome;M. tb is a fastidious slow growing bacterium with long generation time;establishment of productive infection in less than 10% of infected subjects;the bacterium is strictly an intracellular aerobic pathogen;and variable bacteria level of adenosine triphosphate. Opportunities harnessed by M. tb include: development and spread of resistant strains owing to inadequate and inappropriate drug treatment;limited efficacy and use of BCG Vaccine;MDR-TB is under-diagnosed in children;pathogenic synergy of coinfection of the Human Immunodeficiency Virus (HIV) and Mycobacterium tuberculosis (MTB);difficulty of TB screening in HIV-infected persons;immune status of the host;immigration;slow response of the cellular immune response to M. tbwhich enables constant endogenous reinfection of the host;anatomical vulnerability of the lungs;aerosols by inspired air is crucial for latent tuberculosis infection. Threats to M. tuberculosis include: the development and use of sensitive combination of microbiological tests as the gold-standard in HIV infected patients;annual TB test;selective isolation of TB patients by reintroduction of sanatoria;prioritizing genomic drug targets;sustenance of the global TB funds;development of potent vaccine;live imaging using computer tomography and positron electron tomography to characterize active TB in lesions;development and application of Infecton for imaging deep seated infections.

Oxidation of glyoxal to glyoxylic acid by oxygen over V_2O_5/C catalyst

A novel vanadium oxide catalyst supported on active carbon was prepared by an incipient wetness impregnation method, and the precursor was obtained from oxalic acid aqueous solutions of NH4VO3. The catalyst was applied liquid phase oxidation of glyoxal to glyoxylic acid. It was found that V2O5/C catalyst exhibited obvious activity for glyoxal oxidation. Glyoxylic acid could be obtained without pH regulation during the reaction. By using this catalyst, the conversion of glyoxal and the yield of glyoxalic acid were 29.2% and 13.6%, respectively at 313 K and oxygen flow 0.1 L/rain after reaction for 10 h.

Glyoxylic acid as catalyst:A simple selective synthesis of 1,2-disubstituted benzimidazoles in aqueous media

Glyoxylic acid （5 mol%） performs as a novel highly water-soluble catalyst for the synthesis of 2-aryl-l-arylmethyl-lH- benzimidazoles from a wide range of substituted o-phenylenediamines and various substituted aldehydes in good to excellent isolated yields （85-95%） using water as solvent at ambient temperature. The remarkable advantages offered by this method are easily and inexpensive available catalyst, simple procedure, mild conditions, much faster （20--40 rain） reactions and excellent yields of products.

Preparation and Properties of Copper Fine Wire on Polyimide Film in Air by Laser Irradiation and Mixed-Copper-Complex Solution Containing Glyoxylic Acid Copper Complex and Methylamine Copper Complex

Formation of copper wiring on a polyimide film by laser irradiation to a stable copper-complex film consisting of glyoxylic acid copper complex and methylamine copper complex in air has been investigated. A stable metallic copper on the polyimide film was precipitated even in air. Since this copper was generated only in the laser-irradiated parts, direct patterning of copper wiring was possible. It was also found that copper was precipitated by electroless copper plating on the laser-deposited copper wiring and it was possible to thicken the copper wiring by this precipitation. The resistivity of the copper wiring was almost the same as that of the bulk of metallic copper. The developed method—combining laser irradiation to a copper-complex-coated film and electroless copper plating—enables the high-speed deposition of fine copper wiring on a polyimide film in air by a printing process, indicating an inexpensive and useful process for fabricating copper wiring without high vacuum facility and heat-treatment under inert gas.

Fabrication of Copper Wire Using Glyoxylic Acid Copper Complex and Laser Irradiation in Air

Preparation of a glyoxylic acid copper complex and fabrication of fine copper wire by CO2 laser irradiation in air to a thin film of that complex have been investigated. Irradiating laser to the complex thin film spin-coated on a glass substrate, thin film of metallic copper was fabricated in areas that were subjected to laser irradiation in air. The thickness of this thin copper film was approx. 30 to 40 nm, and as non-irradiated areas were etched and removed by a soluble solvent of the copper complex, fine copper wire with 200 μm width was formed by laser direct patterning. The resistivity of this thin copper film depended on the irradiation intensity of the laser and was 3.0 × 10–5 Ω·cm at 12 W intensity (sweep speed: 20 mm/s). This method enables the high-speed deposition of copper wiring in air by a printing process, indicating an inexpensive and useful process for fabricating copper wiring.

Electrocatalytic production of glycolic acid via oxalic acid reduction on titania debris supported on a TiO_(2)nanotube array

Electrodes prepared by anodic oxidation of Ti foils are robust and not toxic materials for the electrocatalytic reduction of oxalic acid to glycolic acid, allowing the development of a renewable energy-driven process for producing an alcoholic compound from an organic acid at low potential and room temperature. Coupled with the electrochemical synthesis of the oxalic acid from CO_(2),this process represents a new green and low-carbon path to produce added value chemicals from CO_(2). Various electrodes prepared by anodic oxidation of Ti foils were investigated. They were characterized by the presence of a TiO_(2) nanotube array together with the presence of small patches, debris, or TiO_(2) nanoparticles. The concentration of oxygen vacancies, the amount of Ti^(3+) measured by X-ray photoelectron spectroscopy(XPS) and the intensity of the anodic peak measured by cyclic voltammetry, were positively correlated with the achieved oxalic acid conversion and glycolic acid yield. The analysis of the results indicates the presence of small amorphous TiO_(2) nanoparticles(or surface patches or debris) interacting with TiO_(2) nanotubes, the sites responsible for the conversion of oxalic acid and glycolic acid yield. By varying this structural characteristic of the electrodes, it is possible to tune the glycolic acid to glyoxylic acid relative ratio. A best cumulative Faradaic efficiency(FE) of about 84% with FE to glycolic acid around 60% and oxalic conversion about 30% was observed.

Synthesis, Characterization and Antibacterial Activity of Mixed Ligand (HL) Complexes Mn(ll), Co(ll), Ni(ll), Zn(ll), Cd(ll) and Hg(ll) with Azide (N₃<sup style="margin-left:-6px;">-</sup>)

The complexes of mixed ligand (HL) as primary ligand with azide ion (N3-) as co-ligand with Mn(ll), Co(ll), Ni(ll), Zn(ll), Cd(ll) and Hg(ll) were prepared via reaction metal (ll) chloride salt with ligand (HL) and sodium azide (NaN3) using 1:2:2 mole ratio in ethanol solvent, respectively. The complexes of mixed ligand (HL) were characterized by elemental microanalysis (C.H.N), atomic absorption chloride content, molar conductance, magnetic susceptibility, melting point, FTIR and UV-Vis spectral data. The anti bacterial activity with four kinds of bacteria, Staphylococcus aureus, Bacillus, Escherichia coli and Pseudomonas aureus was studied.

Exploration of the metabolic flexibility of glycogen accumulating organisms through metatranscriptome analysis and metabolic characterization

Glycogen accumulating organisms(GAOs) are closely related to the deterioration of enhanced biological phosphorus removal systems. However, the metabolic mechanisms that drive GAOs remain unclear. Here, the two-thirds supernatant of a reactor were decanted following the anaerobic period to enrich GAOs. Long-term monitoring demonstrated that the system was stable and exhibited typical characteristics of GAOs metabolism. Acetate was completely consumed after 60 min of the anaerobic phase. The level of glycogen decreased from 0.20 to 0.14 g/gSS during the anaerobic phase, whereas the level of glycogen significantly increased to 0.21g/gSS at the end of the aerobic period. Moreover, there was almost no phosphate release and absorption in the complete periods, thus confirming the successful construction of a GAOs enrichment system. Microbial community analysis demonstrated that Ca. Contendobacter was among the core functional genera and showed the highest activity among all of the communities. Furthermore, our study is the first to identify the involvement of the ethyl-malonyl-CoA pathway in the synthesis of polyhydroxyvalerate via croR, ccr, ecm, mcd, mch and mcl genes. The Embden-Meyerhof-Parnas(EMP) pathway was preferentially used via glgP. Furthermore, the glyoxylate cycle was the main source of ATP under anaerobic conditions, whereas the tricarboxylic acid cycle provided ATP under aerobic conditions. aceA and mdh appeared to be major modulators of the glyoxylate pathway for controlling energy flow. Collectively, our findings not only revealed the crucial metabolic mechanisms in a GAOs enrichment system but also provided insights into the potential application of Ca. Contendobacter for wastewater treatment.

β-Octafluorinated tetrakis(ethoxycarbonyl)porphyrin

Tetrakis（alkoxycarbonyl）porphyrin and its β-octafluoro-substituted derivatives were synthesized via Lindsey method and transformed to their zinc complexes. Single crystal X-ray structures of corresponding Zn（II） porphyrins revealed that β-octafluorination will give more compactness of porphyrin moieties in the crystal structure owing to the hydrogen bonding interactions involving β- fluorine atoms. An unusual six-coordinated Zn（II） was found via intramolecular coordination of oxygen atom of meso-substituents with central Zn（II）.

Using high-throughput data and dynamic flux balance modeling techniques to identify points of constraint in xylose utilization in Saccharomyces cerevisiae

Background Several enzymes and cofactors have been identified as contributing to the slow utilization of xylose by xylose-fermenting strains of Saccharomyces cerevisiae.However,there has been no consensus on which of these possible bottle-necks are the most important to address.A previous strain characterization study from our lab suggested that insufficient NAD+limits fermentation and may be the most important bottleneck affecting utilization of xylose for the production of ethanol.The development and validation of a genome scale dynamic flux balance model would help to verify the existence and extent of this and other metabolic bottlenecks and suggest solutions to guide future strain development thereby minimiz-ing bottleneck impact on process economics.Results A dynamic flux balance model was developed to identify bottlenecks in several strains of S.cerevisiae,both with wild-type pentose phosphate pathway expression and with the pathway over expressed.ZWF1 was found to be limiting in the oxidative portion of the pentose phosphate pathway under oxygen replete conditions.This pathway is used to regenerate NADPH.Under oxygen limiting conditions,respiration of xylose was limited by the lack of oxygen as a terminal electron acceptor.Ethanol production was also limited under these conditions due to the inability to balance NAD+/NADH.The model suggests the use of the anaplerotic glyoxylate pathway to improve NAD+/NADH balance,increasing ethanol produc-tion by 50%while producing succinate as a coproduct at upwards of 20 g/l.Conclusion In the production of high value chemicals from biomass,the use of the respiratory metabolism is a waste of feedstock carbon.Bottlenecks previously identified in the oxidative pentose phosphate pathway are currently only relevant under oxygen-replete conditions and cannot impact the partitioning of carbon between the respiratory and fermentative pathways.Focusing future efforts on the non-respiratory balancing of NAD+/NADH,perhaps through the glyoxylate pathway,would improve the economics of ethanol production both directly and through coproduct formation.

V_2O_5/C catalyst for liquid phase oxidation of glyoxal to glyoxylic acid

A study of the catalytic activity of V2O5/C catalyst for the oxygen oxidation of glyoxal has been made, showing that glyoxylic acid can be formed without control of pH value and there is little oxalic acid from the excessive oxidation of glyoxylic acid. The studies of XRD and TEM have shown that V2O5 diffraction peaks gradually strengthen with the increase of the content of V2O5. With the content of 3% V2O5 and the calcination temperature of 573 K, V2O5/C catalyst displayed the best activity and selectivity. The conversion of glyoxal and the selectivity of glyoxylic acid reached 18.76% and 77.70% after 5 h, respectively. Moreover, V2O5/C catalyst showed small deactivation after recycling three times, which indicates that V2O5/C has a higher stability than noble metal catalysts in the reaction medium.