Substituting Both the N-Terminal and “Cord” Regions of a Xylanase from <Emphasis Type="Italic">Aspergillus oryzae</Emphasis> to Improve Its Temperature Characteristics

To improve the temperature characteristics of AoXyn11A, a mesophilic glycoside hydrolase family (GHF) 11 xylanase from Aspergillus oryzae CICC40186, its N-terminal and “cord” regions were selected to be substituted by means of the computer-aided analysis and calculation. In brief, one mutant, named ATX11A⁴¹, possessing the lowest root-mean-square deviation (RMSD) value was designed based on the molecular dynamics (MD) simulation by substituting the N-terminal 41 amino acids of AoXyn11A with the corresponding 42 ones of pXYL11, a thermophilic GHF11 xylanase from Thermobifida fusca. On the basis of the primary structure alignment of pXYL11 with ATX11A⁴¹ (or AoXyn11A), another mutant, named ATX11A^41/cord, was designed by substituting the cord region (⁹³GTYNPGSGG¹⁰¹) of ATX11A⁴¹ with the corresponding one (⁹³GTYRPTG⁹⁹) of pXYL11. Both mutant-encoding genes, ATx11A⁴¹ and ATx11A^41/cord, were constructed as designed theoretically by a megaprimer PCR technique and were expressed in Pichia pastoris GS115. The specific activities of recombinant (re) AoXyn11A, ATX11A⁴¹, and ATX11A^41/cord were 2916.7, 2667.6, and 2457.0 U/mg, respectively. The analysis of temperature characteristics displayed that the temperature optimum (T_opt) of reATX11A⁴¹ or reATX11A^41/cord was 65 °C, which was 15 °C higher than that of reAoXyn11A. The thermal inactivation half-life (t_1/2) values of reATX11A⁴¹ and reATX11A^41/cord at 60 °C were 55 and 83 min, respectively, whereas that of reAoXyn11A was only 18 min at 50 °C. The melting temperature (T_m) values of reAoXyn11A, reATX11A⁴¹, and reATX11A^41/cord were 54.2, 66.7, and 71.9 °C, respectively. In conclusion, the above findings indicated that the substitution of both the N-terminal and cord regions of a mesophilic AoXyn11A greatly contributed to its improved temperature characteristics.     

Synthesis and Anticancer Activity of 1,2,3-Triazole Fused N-Arylpyrazole Derivatives

A novel series of triazole derivatives 11a–11j is synthesized. Structures of the products are confirmed by ¹H and ¹³C NMR, and mass spectral data. The anticancer activities of compounds 11a–11j are evaluated against three human cancer cell lines (MCF-7, A549, and A375) using the standard MTT assay in vitro, using doxorubicin as the positive control. All the compounds exhibit significant activity against cancer cell lines. The compounds 11a, 11d, 11e, 11g, and 11j demonstrate more potent activity than the positive control.

     

Organoplatinum‐Substituted Polyoxometalate Inhibits β‐amyloid Aggregation for Alzheimer's Therapy

Aggregated β‐amyloid (Aβ) is widely considered as a key factor in triggering progressive loss of neuronal function in Alzheimer's disease (AD), so targeting and inhibiting Aβ aggregation has been broadly recognized as an efficient therapeutic strategy for curing AD. Herein, we designed and prepared an organic platinum‐substituted polyoxometalate, (Me₄N)₃[PW₁₁O₄₀(SiC₃H₆NH₂)₂PtCl₂] (abbreviated as Pt^II‐PW₁₁) for inhibiting Aβ₄₂ aggregation. The mechanism of inhibition on Aβ₄₂ aggregation by Pt^II‐PW₁₁ was attributed to the multiple interactions of Pt^II‐PW₁₁ with Aβ₄₂ including coordination interaction of Pt²⁺ in Pt^II‐PW₁₁ with amino group in Aβ₄₂, electrostatic attraction, hydrogen bonding and van der Waals force. In cell‐based assay, Pt^II‐PW₁₁ displayed remarkable neuroprotective effect for Aβ₄₂ aggregation‐induced cytotoxicity, leading to increase of cell viability from 49 % to 67 % at a dosage of 8 μm . More importantly, the Pt^II‐PW₁₁ greatly reduced Aβ deposition and rescued memory loss in APP/PS1 transgenic AD model mice without noticeable cytotoxicity, demonstrating its potential as drugs for AD treatment.     

The Simultaneous Determination of Δ9-Tetrahydrocanna-Binol and 11-Hydroxy -Δ9 -Tetrahydrocannabinol in Plasma

Abstract

A technique capable of determining both Δ⁹-tetrahydrocannabinol and 11-hydroxy-Δ⁹-tetrahydrocannabinol is described. The method is based on the reactivity of the phenolic functionality common to both compounds, and is sensitive to 5 ng of Δ⁹-tetrahydrocannabinol and 1 ng of 11-hydroxy-Δ⁹-tetrahydrocannabinol per ml of plasma.     

1H, 13C, 19F and 11B NMR spectral reference data of some potassium organotrifluoroborates

Complete ¹H, ¹³C, ¹⁹F and ¹¹B NMR spectral data for 28 potassium organotrifluoroborates are described. The resonance for the carbon bearing the boron atom is described for most of the studied compounds. A modified ¹¹B NMR pulse sequence was used and better resolution was observed allowing the observation of ¹¹B–¹⁹F coupling constants for some of the studied compounds. Copyright © 2009 John Wiley & Sons, Ltd.     

Undecahalo‐closo‐undecaborates [B11Hal11]2–

The closo‐undecaborate A₂[B₁₁H₁₁] (A = NBzlEt₃) can be halogenated with excess N‐chlorosuccine imide, bromine or iodine, respectively, to give the perhalo‐closo‐undecaborates A₂[B₁₁Hal₁₁] (Hal = Cl, Br, I). The chlorination in the 11 : 1 ratio of the reagents yields A₂[B₁₁HCl₁₀], whose subsequent iodination makes A₂[B₁₁Cl₁₀I] available. The three type [B₁₁Hal₁₁]^2– anions show only one and the two type [B₁₁Cl₁₀X]^2– anions (X = H, I) only two ¹¹B NMR peaks in the ratio 10 : 1, thus exhibiting the same degenerate rearrangement of the octadecahedral B₁₁ skeleton as is well‐known for [B₁₁H₁₁]^2–. The crystal structure analysis of A₂[B₁₁Br₁₁] and A₂[B₁₁I₁₁] reveals a rigid octadecahedral skeleton in the solid state, up to 330 K, whose B–B bond lengths deviate more or less from the idealized C_2v gas phase structure, but are in good accordance with the distances of A₂[B₁₁H₁₁]. Electrochemical experiments elucidate the mechanism of the known oxidation of [B₁₁H₁₁]^2– to give [B₂₂H₂₂]^2–: A first one‐electron transfer is followed by the dimerization of the [B₁₁H₁₁]^– monoanion, whereas neutral B₁₁H₁₁, a presumably most reactive species, does not play a role as an intermediate. The electrochemical oxidation of [B₁₁Hal₁₁]^2– anions also starts with a one‐electron transfer, which is perfectly reversible only in the case of Hal = Br. There is no electrochemical indication for the formation of [B₂₂Hal₂₂]^2–. The neutral species B₁₁Hal₁₁ should be a short‐lived, very reactive species.     

The determination of boron in rocks by deuteron activation analysis

The determination of boron in rocks by charged particle activation using the¹⁰B(d, n)¹¹C reaction is studied. A sample holder that allows reproducible irradiation of powdered samples is developed.¹¹C is separated as¹¹CO₂. For boron concentrations between 2.35 and 25.2 μg·g⁻¹, the standard deviations ranges from 7.1 to 22.8%. The results for USGS reference silicate rocks and Moroccan phosphate rock are compared to those obtained by other techniques.     

柱撑阴离子粘土的合成、表征及催化性能研I.ZnAl─SiW11及ZnAl—SiW11Z的合成

采用水热合成及离子交换方法将缺位及单取代型Keggin结构钨硅杂多含氧酸根SiW₁₁及SiW₁₁O₃₉Z(H₂O)^6-嵌入Zn─Al型阴离子粘土层间,得到了大层间距的新型层往状微孔材料ZnAl─SiW₁₁及ZnAl-SiW₁₁Z(Z=Co²⁺、Ni²⁺和Cu²⁺),XRD与IR测试结果表明,它们只有9.7Å 的通道高度.     

Ruthenium complexes with heteropoly anion PW11O39 7− and their redox properties

A new heteropoly complex PW₁₁Ru^IV and complexes of Ru^II, Ru^III and Ru^V based thereon have been obtained. Using specrophotometry the states of Ru^III and Ru^IV complexes in solution, the pH range of their stability, and the interaction of PW₁₁Ru^IV with ClO₄ ^–,SO₄ ^2–, Cl^– ions have been studied. A conclusion has been thus made that the ruthenium ion in such a complex is not incorporated in the heteropolyanion lattice, but is attached only to its external oxygen atoms. Kinetics of oxidation of PW₁₁Ru^IV and PW₁₁Ru^III with potassium chlorate have been studied. The activation energy and pre-exponential factor have been found for the reaction. The possibility that ClO₄ ^– and ClO₃ ^– in aqueous solutions can be activated by PW₁₁Ru^II with the former and by PW₁₁Ru^III and PW₁₁Ru^IV with the latter has been demonstrated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1363–1369, August, 1993.The authors wish to thank I. L. Krayevskaya and V. M. Novopashina for X-ray fluorescence and ionic chromatographic analyses, respectively.     

A simplified [11C]phosgene synthesis

A new flow-through system for the production of [¹¹C]phosgene, a versatile labelling agent in radiochemistry for PET, is described. Cyclotron-produced [¹¹C]CH₄ is mixed with Cl₂ and converted into [¹¹C]CCl₄ by passing the mixture through an empty quartz tube at 510 °C. The outflow is directed through a Sb-filled guard that takes out Cl₂ and then, without intentional O₂ addition, through a second empty quartz tube at 750 °C, giving rise to [¹¹C]phosgene in 30–35% radiochemical yield.     

High-resolution infrared measurements of v1 and force field calculations for thioborine (HBS)

The gas-phase high-resolution spectrum is reported for v₁ of the linear molecule thioborine (HBS) from 2775 cm^?1 to 2720 cm^?1. Band centers and rotational constants are given for the 10⁰0-00⁰0 transitions of H¹¹B³²S, H¹⁰B³²S, H¹¹B³⁴S and H¹⁰B³⁴S and for the 11¹0-01¹0 transitions of H¹¹B³²S and H¹⁰B³²S. A valence force field is determined from measured values of v₁, D_o (the centrifugal distortion) and q (the l-doubling constant). The remaining unobserved vibrational fundamentals are calculated from the force constants.     

Vibrational energy-harvesting performance of bio-sourced flexible polyamide 11/layered silicate nanocomposite films

The energy-harvesting efficiency of melt processed polyamide 11 (PA11) films and its nanocomposites have been investigated as a function of filler type and content. In the present work, nanoclays have been used as structural modifiers in a PA11 matrix. The nanocomposites were prepared using layered clays, Cloisite 20A, 10A, and Na⁺, by extrusion process through varying the filler content, 1, 2, 4, and 5?wt.%. The crystalline structure of these nanocomposites has been studied by X-ray diffractometer. It has been demonstrated that layered silicates are not significant for the structural quality of the obtained nanocomposites. Regarding the interlayer peak of different clays, it has also been revealed that Cloisite 20A is partially exfoliated, whereas 10A and Na⁺ are totally exfoliated in the PA11 matrix. From mechanical and dynamic mechanical analyses, it was found that the addition of layered silicates results in an increase in mechanical properties. The piezoelectric strain coefficient d₃₃ and dielectric constant ε_R have been measured on polarized films at ambient temperature. Among all the prepared nanocomposites only Cloisite Na⁺-loaded PA11 nanocomposites showed the best piezoelectric constant. This observation showed that piezoelectric constant not only depends on the crystalline phases but also on the nature of the filler. Cloisite Na⁺ is more polar than other modified clays and high polarity leads to a better polarization response. A specific method for the quantification of energy vibration recovery has been developed for these nanocomposites. The capabilities of vibrational energy recovery were studied on PA11 loaded with Cloisite Na⁺.     

Involvement of histidines 11, 15 and 19 in the binding of zinc to the fusogenic H5WYG peptide

The histidine‐rich GLFHAIAHFIHGGWHGLIHGWYG peptide (H5WYG) coordinates a Zn²⁺ ion and forms a stable peptide–metal complex promoting membrane fusion at physiologic pH. In our previous article titled ‘Histidine‐rich peptide: evidence for a single zinc‐binding site on H5WYG peptide that promotes membrane fusion at neutral pH’ in Journal of Mass Spectrometry (2009, 44, 81–89), tandem mass spectrometry experiments have provided evidence for the binding of a single Zn²⁺ ion to H5WYG and suggested that this binding is shared between H¹¹, H¹⁹ and probably H¹⁵ residues. To clarify the involvement of these histidine residues in the binding to the Zn²⁺ ion and especially to remove the doubt about the implication of the H¹⁵ residue, here we have used three H5WYG mutants termed H5WYGH11A, H5WYGH15A and H5WYGH19A, whose H¹¹, H¹⁵ and H¹⁹ residues were replaced with an alanine residue. The novelty introduced by these new tandem mass spectrometry experiments performed with the mutants is the demonstration that H¹⁵ is involved in the binding of the single Zn²⁺ ion and that it may even favour the setting of another Zn²⁺ ion. Thus, the three histidines H¹¹, H¹⁵ and H¹⁹ could lead to a specific structuring of H5WYG that can promote membrane fusion upon the binding of zinc. Copyright © 2009 John Wiley & Sons, Ltd.     

Remote controlled unit for the production of [2-11C] isopropyl iodide

A remote controlled system is described for the production of [2-¹¹C] isopropyl iodide. The synthesis involves carbonation of methyl lithium with¹¹CO₂ followed by reduction with lithium aluminum hydride, hydrolysis and iodination with hydroiodic acid. The purification is performed by preparative gaschromatography on a Chromosorb 102-Porapak Q column. For a 30 min irradiation at 15 A beam intensity the method yields about 300 mCi /11 GBq/ of radiochemically and chemically pure [2-¹¹C] isopropyl iodide with a specific activity of 210 to 250 mCi. mol^–1 at the end of synthesis /EOB+25 min/. The remote controlled unit is also useful for the production of other alkyl iodides, acetone and acetic acid, labelled with¹¹C.     

Elucidation of structures of nido-y-CB8H12 and B9H−12 by two-dimensional 11B-11B NMR spectroscopy

The product of the thermal decomposition of 4-CB₈H₁₄ is, according to two-dimensional (2-D) ¹¹B-¹¹B NMR spectroscopy, 7-CB₈H₁₂. An analogous strutcure stems from the 2-D NMR for B₉H⁻₁₂. A new approach to the estimation of distribution of bonds in borane skeletons is proposed on the grounds of positions of individual signals in the given ¹¹B NMR spectrum and documented in the distribution of bonding electrons in B₉H⁻₁₂ and 7-CB₈H₁₂.     

Yield ratio of [11C]-CO2, [11C]-CO and [11C]-CH4 from the irradiation of N2/H2-mixtures in a gas target

The¹⁴N/p, /¹¹C-reaction was studied in different N₂/H₂-mixtures. The products are [¹¹C]-CO₂, [¹¹C]-CO and [¹¹C]-CH₄. The yield ratio may be controlled by varying the bombardment conditions. High pressure, high H₂-content, high beam current and high proton energy shift the ratio towards [¹¹C]-CH₄. Lower beam current and lower proton energy increase the yield of [¹¹C]-CO₂. The production of [¹¹C]-CO is constant over a wide range of conditions /about 10%/. For the production of [¹¹C]-CH₄ in good yield a target gas holder for high pressures has been developed. Details are given in Fig. 7. This target gas holder was filled with 5% H₂ in N₂ at 3×10⁶ Pa. Proton irradiation of the mixture gives a typical yield of [¹¹C]-CH₄ of 400–500 mCi at a beam current of 15–20 A within 20 min. Only traces of other¹¹C-labelled compounds could be detected under these conditions.     

Application of Methyl Bisphosphine‐Ligated Palladium Complexes for Low Pressure N‐11C‐Acetylation of Peptides

A mild and effective method is described for ¹¹C‐labeling of peptides selectively at the N‐terminal nitrogen or at internal lysine positions. The presented method relies on the use of specific biphosphine palladium–methyl complexes and their high reactivity towards amino‐carbonylation of amine groups in the presence [¹¹C]carbon monoxide. The protocol facilitates the production of native N‐¹¹C‐acetylated peptides, without any structural modifications and has been applied to a selection of bioactive peptides.     

Amide derivatives of 4-azaindole: Design,synthesis, and EGFR targeting anticancer agents

Abstract

A series of amide derivatives of azaindole-oxazoles (11a-n) were designed and synthesized and their structures were confirmed by ¹HNMR, ¹³CNMR and mass spectral analysis. Further, these derivatives were screened for their anticancer activity against human cancer cell lines viz; MCF7 (breast), A549 (lung) and A375 (melanoma). In vitro anticancer activity screening indicated that most of the hybrids exhibited potent inhibitory activities in a variety of cancer cell lines. Among the compounds 11d, 11e, 11f, 11j, 11k, 11l, 11m, and 11n were exhibited more potent activity than standard, in those mainly two compounds 11m and 11j were exhibited excellent activity in MCF-7 cell line with IC₅₀ values 0.034 and 0.036?µM. Moreover, all these compounds were carried out their molecular docking studies on EGFR receptor results indicated that two potent compounds 11m and 11j were strongly binds to protein EGFR (PDB ID: 4hjo). It was found that the energy calculations were in good agreement with the observed IC₅₀ values.     

Trace determination of beryllium by heavy ion activation analysis

A novel procedure for measuring the concentration of trace beryllium in different samples has been studied using¹¹B heavy ion activation analysis. The specific reaction,⁹Be/¹¹B, 2n/¹⁸F, is sensitive and selective when using a 10 MeV¹¹Be³⁺ bombardment energy. The detection limit for a nondestructive analysis is 0.1 ng for a 2 h irradiation in a A cm^–2 beam current. A precision of 12% was achieved at the 50 g g^–1 level. Beryllium has been determined in a standard beryllium-copper alloy NBS-SRM C1123. Glass samples containing up to 61 trace elements were also analyzed nondestructively. When using a clean vacuum irradiation chamber, the technique might allow ultra-trace determinations, dealing with solid samples of a few milligrams.     

Rapid synthesis of C-labeled FK506 for positron emission tomography

The present study describes a rapid synthesis method for labeled [¹¹C]FK506 for positron emission tomography (PET). A one-pot reaction from [¹¹C]CH₃I, involving a Wittig reaction as the key carboncarbon bond formation was developed. The chemical process was accomplished using a designed, fully automated synthetic apparatus, and an injectable solution of [¹¹C]FK506 was obtained in only 34 min from [¹¹C]CH₃I. The decay-corrected radiochemical yield based on [¹¹C]CH₃I was 11.9%, and the specific activity was 39.8 GBq/μmol.