Water Diffusion In And Out Of The β-Barrel Of GFP and The Fast Maturing Fluorescent Protein, TurboGFP

The chromophore of fluorescent proteins is formed by an internal cyclization of the tripeptide 65SYG67 fragment and a subsequent oxidation. The oxidation is slow - the kinetics of this step is presumably improved in fast maturing GFPs. Water molecules can aid in the chromophore formation. We have used 50 ns molecular dynamics simulations of the mature and immature forms of avGFP and TurboGFP to examine the diffusion of water molecules in-and-out of the protein β-barrel. Most crystal structures of GFPs have well-structured waters within hydrogen-bonding distance of Glu222 and Arg96. It has been proposed that they have an important role in chromophore formation. Stable waters are found in similar positions in all simulations conducted. The simulations confirm the existence of a pore that leads to the chromophore in the rapidly maturing TurboGFP; decreased water diffusion upon chromophore formation; and increased water diffusion due to the pore formation.     

Hydrogen evolution reaction on Sn, In, and Sn–In alloys in carboxylic acids

The cathodic behavior of tin, indium, and tin–indium alloys in 0.5-M solutions of oxalic, malic, and citric acids has been investigated using potentiodynamic techniques at temperature range of 30–60 °C. The results showed that the corrosion rate (I _corr) is higher at lower indium percent (0.5% In) and starts to decrease gradually as increase of the In percent up to 5% In (although it is still higher than that of pure tin and lower than that of indium at 5% In) in all examined acids. The positive shift in corrosion potential with simultaneous increase in corrosion rate can be explained on the basis of the depolarizing action of β-InSn₄ phase compared with pure tin. The negative shift in the corrosion potential with much higher corrosion rate in case of alloys IV and V (10% and 20% In, respectively) can be ascribed to the formation of γ-In₃Sn phase which leads to the increase in the anodic to cathodic area ratio. The corrosion of the two investigated metals and their alloys is affected by the formation of soluble complex species with organic acid anions. The aggressiveness of the studied metals and their alloys decreases in the following order of the organic acids employed oxalic > malic > citric acid. The observed activation energy values support that the tested electrodes exhibit higher corrosion rates in oxalic acid solution than the corresponding values in the other investigated acids. X-ray diffraction and scanning electron microscopy photographs elucidated the types of phases formed in the prepared alloys. The presence of a definite amount of indium in tin alloy improves the hardness.     

A Proline-Based Aminophosphinic Acid Ligand and It’s Vanadyl Complex: Synthesis,Characterization and In Vitro Inhibitory Effects on α-Amylase And α-Glucosidase

Abstract

A proline-based aminophosphinic acid ligand and it's vanadium complex have been synthesized and characterized by spectroscopic techniques. The inhibitory activity on pancreatic α-amylase and Baker's yeast α-glucosidase has been examined in vitro. The novel complex showed more inhibitory potency against pancreatic α-amylase and Baker's yeast α-glucosidase compared to acarbose as an antidiabetic drug.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Intramolecular Hydrogen Bonding In N-(2-Amino-2-Deoxy-β-D-Glucopyranoside)-N'-Carbamoyl-L-Dipeptidylesters: An Infrared And 1H Nmr Study

ABSTRACT

Ten N-(2-amino-2-deoxy-β-D-glucopyranoside)-N'-carbamoyl-L-dipeptidylesters with different amino acid sequences in the dipeptide unit were studied by means of IR and ¹H NMR spectroscopy. In the IR spectra three bands at 3453, 3420 and 3390 cm^-1 were observed which could be assigned to the free NH, the intramolecularly hydrogen bonded NH species forming five-membered, C₅, and seven-membered, C₇, rings, respectively. Comparing the NH band positions which correspond to the C₇ rings of the Gly-Xaa and the Xaa-Gly dipeptidylesters, the signals of the Xaa-Gly sequence were shifted by 10 cm^-1 to lower wave numbers indicating stronger hydrogen bonds. The temperature effect dv/dT was an order of magnitude larger for the C₇ associates than for C₅ showing the highest enthalpy of the C₇ hydrogen bond. The ¹H NMR spectra give three separate signals for the NH groups. The temperature coefficient ?δ/?T was the largest for N-1-H indicating the formation of less stable hydrogen bonds (C₇). The solvent induced changes of the chemical shift of the NH signals was lowest for the N-3-H signal. Obviously the deshielding properties on this function do not vary in dependence of the solvent polarity. The hydrogen/deuterium exchange rate was lowest for the N-6-H proton indicating the lower accessibility of this proton. Combining the results of both spectroscopic methods it can be concluded that the N-1-H forms only C₇ rings whereas N-6-H can participate in C₅ and C₇ intramolecular hydrogen bonds. The strength of the formed C₇ associates depends on the amino acid sequence in the dipeptide residue.     

In This Issue

封面:稀土是重要的稀有元素,资源有限,稀土催化材料是稀土资源尤其是高丰度轻稀土元素(镧、铈、镨等)重要的应用领域.为了反映稀土催化研究的新进展,推进稀土催化材料的发展,本期邀请了在稀土催化研究中比较活跃的课题组撰写了16篇文章组成稀土催化专刊,其中包括2篇综述、1篇快讯和13篇论文,内容主要涉及环境催化、石油化工和能源化工催化等过程.     

In This Issue

<正>封面:Kannan教授及其合作者分析了用于质子交换膜燃料电池和碱性膜燃料电池纳米催化剂的研究现状,介绍了几种贵金属和非贵金属催化剂的合成方法,并讨论了用于原位和非原位表征这些催化材料的各种方法.见本期第458–472页.Cover:Prof.Kannan and his coworkers in their Review on pages458–472 analyzed the current status of nanocatalysts for proton exchange     

In This Issue

封面:贺泓及研究团队基于实验室对VWOTiO催化剂配方及涂覆成型技术的大量研究,在中国重汽集团建成了一条NHSCR催化剂生产线,产品满足国产重型柴油车国IV排放标准要求.见本期第1438–1445页.Cover:Prof.He and his coworkers in their Article on pages 1438–1445reported the laboratory study of catalyst formulation and washcoating technologyfor the VWOTiOsystem,and also the establishment of an NHSCR(selective catalytic reduction of NOwith NHcatalyst production line of     

Study On The Catalytic Reaction Of β-Cd-Hemin Using 2, 3, 4-Trichlorophenol As Substrate And Analytic Application

ABSTRACT|The catalytic activity of various mimetic enzymes instead of the peroxidase have been investigated by 4-aminoantipyrine (4-AAP) and 2, 3, 4-trichlorophenol (TCP) to form a dye utilizing hydrogen peroxide as hydrogen acceptor. The different Chlorophenolic derivatives, which act as a substrate in β-CD-hemin-H₂O₂-4-AAP catalytic reaction, have been systematically studied.|Meanwhile, the relationship of structure-effect for the β-CD-hemin as catalyst, and chlorphenols as substrate has been respectively discussed. The mechanism of catalytic reaction has been investigated. The results showed that β-CD-hemin was the best mimetic enzyme for peroxidase among those tested and TCP was a good substrate for the determination of hydrogen peroxide with β-CD-hemin. The method for the determination of hydrogen peroxide was proposed using 4-AAP-TCP system with β-CD-hemin as catalyst. A linear calibration graph was obtained over the H₂O₂ concentration of 4.8×10-^?8-7.7×10-^?5M, and the relative standard deviation at a H₂O₂ concentration of 2.8×10-^?5M was 2.5%. The apparent molar absorptivity of the chromogenic reaction for H₂O₂ was 1.54× 10⁴ L.mol-^?1.cm^?1. Satisfactory results were obtained in the determination of H₂O₂ in synthetic samples by this method.

Also, the method was coupled with the glucose oxidation reaction to determination glucose in human serum.     

Contracted polarization functions for the atoms Ca, Ga–Kr, Sr, and In–Xe

 Contracted Gaussian-type function sets are proposed for polarization functions of the atoms Ga–Kr and In–Xe. We also report polarization functions for Ca and Sr. A segmented contraction scheme is used for its compactness and computational efficiency. The contraction coefficients and orbital exponents are fully optimized to minimize the deviation from accurate atomic natural orbitals. The present polarization functions yield more than 99% of atomic correlation energies predicted by accurate natural orbitals of the same size. Received: 23 February 2001 / Accepted: 19 April 2001 / Published online: 13 June 2001     

The Electrochemical Oxidation And Analytical Application Of Cholesterol

Cho1esterolisanimportantsubstanceinbiochemistryandclinicalfields.Sotostudyanddevelopasensitivemethodforthedeterm1nationofchoIesterolhasattractedconsiderableattention.Overtheyears,variousmethodshavebeenreportedforthedeterminationofcholesterol-Thesemethodsincludeen-zymemethodand8pectrophotometry['3.Apulsepolarographicmethodshasal-sobeenreported['J.Butno2.5orderdifferentialstrippingvoltammetryforthedeterminationofcholestero1hasbeenrepJrted.Inourstudy,itwasfoundthatcholestero1couldbeadsorbedonth…     

Synthesis of γ-Polynitrocarboxylic Acids And Derivatives Thereof

A synthesis of new branched -nitrocarboxylic acids and their derivatives (nitriles, amides, trinitroethyl esters) was developed proceeding from the corresponding aldehydes obtained by nitroform or 1,1-dinitroethane addition to 2-(2,2-dinitropropyl)acrylic aldehyde according to Michael reaction.     

Synthesis,In Vitro α-Amylase Activity,and Molecular Docking Study of New Benzimidazole Derivatives

Russian Journal of Organic Chemistry - New benzimidazole derivatives were synthesized by reacting substituted phenacyl bromides with 1H-benzimidazole-2-thiols. The synthesized compounds were...     

Preparation And Characterization of a New Blend of Poly(2-hydroxyethyl methacrylate) And Poly(ethylene glycol)

Poly(2-hydroxyethylmethacrylate)(PHEMA)isahydroge1widelyusedinthefieldsofcontactlenses,atificialcorneasandsofttissuesubstitutes.However,theuseofPHEMAhydrogelisrestrictedduetoitsinsufficientlypermeablecharacterandlimitedwaterintake.Therefore,modificationsofthePHEMAhydrogelp1ayakeyroleinitspracticalaPplications'.Poly(ethyleneglycol)(PEG)isanonionicwatersolublematerialthathascomplexsolubilityproperties'.Meanwhile,PEGisnontoxic.Water-swellable,water-insolublehydrogelsmaybemadefromPEGbym…     

In Schiefer?l

Ohne Zusammenfassung     

Rolf Huisgen,Eminent Chemist and Polymath (1920–2020): In His Own Words and In His Publication Metrics

As a compliment to several other publications that present and honor Rolf Huisgen's research achievements, the first part of this paper reveals the human side of this eminent chemist. From excerpts from many of his personal and professional writings, Huisgen's personality and philosophies of life are revealed. Also revealed is Huisgen functioning as a historian of chemistry. The second part of this paper examines the scientometrics of Huisgen's publication history. In the late 1950s and early 1960s, Huisgen's career experienced a major transition in terms of publication metrics and the influence these papers had on the organic chemistry community. This was the result of his research into 1,3-dipolar cycloadditions. Citations to his scientific contributions are well spread over many of his papers, demonstrating his constant work and the building up of a research topic, which continued after his official retirement in 1988. In fact, 17 % of his more than 600 publications appeared after 1988. The majority of Huisgen's papers were co-authored with his many graduate and postdoctoral students. Consistent with the trend of that era, Huisgen was the sole author of most of his Review articles, and not just those of his many plenary lectures, and it is those Review articles that proved to be his most cited publications. This demonstrates the power and influence of Review articles—secondary sources, in the vocabulary of historians and sociologists of science. In those Review articles, Huisgen principally described the state of the art of 1,3-dipolar cycloadditions—his golden offspring.     

Potential Biodegradable Implants from ϵ-Caprolactone and D,L-Lactide Copolymers: Synthesis,Properties, and In Vivo Degradation

Random copolymers of ?-caprolactone (CL) and D, L-lactide (DLLA) were synthesized by ring-opening polymerization using stannous octoate as catalyst. The effect of polymerization conditions, such as feeding dose, reaction temperature, polymerization time, and catalyst content on the properties of the copolymers was evaluated to prepare suitable copolymers with controlled properties for biodegradable implant applications. The results showed that the polymerization conditions influenced the thermal and mechanical properties of the copolymers strongly and controllable and tunable properties of random copolymers could be obtained by adjusting the copolymer compositions. The optimum reaction conditions to prepare the CL-DLLA copolymers for implant applications are 30–87 mol.% DLLA content in feeding dose, 110°C reaction temperature, and 24 h polymerization time. The results of in vivo implantation revealed the excellent degradability of CL-DLLA copolymers. Copolymers of CL and DLLA with different compositions and properties would be suitable for the application of biodegradable implants.     

Eine schnelle spektrographische Bestimmung von In, Tl, Te und As in technologischen L?sungen

Ohne Zusammenfassung     

CuI-Catalyzed,One-Pot,Three-Component Huisgen Cycloaddition Reaction of Conjugated Enynes and In Situ–Generated Azides

A novel and efficient copper(I)-catalyzed three-component Huisgen cycloaddition reaction of conjugated enynes, alkyl halides, and sodium azide has been developed. These reactions were performed in the absence of amide ligands at room temperature, and the corresponding mono- and bis-1,2,3-triazoles were obtained in good to excellent yields in a one-pot procedure.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.