- Molecularly Imprinted Synthetic Glucosidase for the Hydrolysis of Cellulose in Aqueous and Nonaqueous Solutions
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Molecular imprinting is a powerful and yet simple method to create multifunctional binding sites within a cross-linked polymer network. We report a new class of synthetic glucosidase prepared through molecular imprinting and postfunctionalization of cross-linked surfactant micelles. These catalysts are protein-sized water-soluble nanoparticles that can be modified in multiple ways. As their natural counterparts, they bind a glucose-containing oligo- or polysaccharide. They contain acidic groups near the glycosidic bond to be cleaved, with the number and distance of the acid groups tuned systematically. Hydrolysis of cellulose in a key step in biomass conversion but is hampered by the incalcitrance of the highly crystalline cellulose fibers. The synthetic glucosidases are shown to hydrolyze cellobiose and cellulose under a variety of conditions. The best catalyst, with a biomimetic double acid catalytic motif, can hydrolyze cellulose with one-fifth of the activity of commercial cellulases in aqueous buffer. As a highly cross-linked polymeric nanoparticle, the synthetic catalyst is stable at elevated temperatures in both aqueous and nonaqueous solvents. In a polar aprotic solvent/ionic liquid mixture, it hydrolyzes cellulose several times faster than commercial cellulases in aqueous buffer. When deposited on magnetic nanoparticles, it retains 75% of its activity after 10 cycles of usage.
- Li, Xiaowei,Zangiabadi, Milad,Zhao, Yan
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p. 5172 - 5181
(2021/05/04)
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- Increased endothelial cell selectivity of triazole-bridged dihalogenated A-ring analogues of combretastatin A-1
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The antiproliferative activity on ovarian cancer (SK-OV-3) cells of a series of triazole-bridged combretastatin analogues (37, 38, 40-43) containing dihalogenation of the A-ring is reported, and compared with their trimethoxy analogues (5, 15, 39). It was found that dihalogenation with either bromine or iodine was a tolerated modification when compared to the parent compound combretastatin (CA-4, 1) and had less effect than B-ring modification on potency. These compounds exhibited G2/M arrest, and maintained antitubulin activity. Further assays on human umbilical vein endothelial cells (HUVECs) demonstrated the potential antivascular effects of these triazoles. Of particular note was a 3,5-diiodo-4-methoxyaryl triazole (43) which had promising 7-fold selectivity for HUVECs over ovarian cancer cells.
- Beale, Thomas M.,Bond, Peter J.,Brenton, James D.,Charnock-Jones, D. Stephen,Ley, Steven V.,Myers, Rebecca M.
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p. 1749 - 1759
(2012/04/10)
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- A-ring dihalogenation increases the cellular activity of combretastatin-templated tetrazoles
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The combretastatins have been investigated for their antimitotic and antivascular properties, and it is widely postulated that a 3,4,5-trimethoxyaryl A-ring is essential to maintain potent activity. We have synthesized new tetrazole analogues (32a€"34), demonstrating that 3,5-dihalogenation can consistently increase potency by up to 5-fold when compared to the equivalent trimethoxy compound on human umbilical vein endothelial cells (HUVECs) and a range of cancer cells. Moreover, this increased potency offsets that lost by installing the tetrazole bridge into combretastatin A-4 (1), giving crystalline, soluble compounds that have low nanomolar activity, arrest cells in G2/M phase, and retain microtubule inhibitory activity. Molecular modeling has shown that optimized packing within the binding site resulting in increased Coulombic interaction may be responsible for this improved activity.
- Beale, Thomas M.,Allwood, Daniel M.,Bender, Andreas,Bond, Peter J.,Brenton, James D.,Charnock-Jones, D. Stephen,Ley, Steven V.,Myers, Rebecca M.,Shearman, James W.,Temple, Jill,Unger, Jessica,Watts, Ciorsdaidh A.,Xian, Jian
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p. 177 - 181
(2012/05/05)
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- Oxidative iodination of deactivated arenes in concentrated sulfuric acid with I2/NaIO4 and KI/NaIO4 iodinating systems
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Deactivated arenes were mono- or diiodinated with strong electrophilic I+ reagents, which were prepared from NaIO4 and either I2 or KI in concentrated H2SO4 (minimum 95% by weight). In general a small excess of the dark brown iodinating solution was used (1.1/1.5 equivalents, for nitrobenzene two equivalents was required). The iodinations were conducted at 25-30 °C with a reaction time of 1-2 hours using either a 'direct' or an 'inverse' method of aromatic iodination to give mono- or diiodinated pure products in 31-91% optimized yields. Georg Thieme Verlag Stuttgart.
- Kraszkiewicz, Lukasz,Sosnowski, Maciej,Skulski, Lech
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p. 1195 - 1199
(2007/10/03)
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- Easy, inexpensive and effective oxidative iodination of deactivated arenes in sulfuric acid
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Two 'model' deactivated arenes, benzoic acid and nitrobenzene, were effectively monoiodinated within 1 h at 25-30 °C, with strongly electrophilic I+ reagents, prior prepared from diiodine and various oxidants (CrO3, KMnO4, active MnO2, HIO 3, NaIO3, or NaIO4) in 90% (v/v) concd sulfuric acid (ca. 75 mol% H2SO4). Next, an I2/ NaIO3/90% (v/v) concd H2SO4 exemplary system was used to effectively mono- or diiodinate a number of deactivated arenes. All former papers dealing with the direct iodination of deactivated arenes are briefly reviewed.
- Kraszkiewicz, Lukasz,Sosnowski, MacIej,Skulski, Lech
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p. 9113 - 9119
(2007/10/03)
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- 2,6-diiodo-4-nitrophenol, 2,6-diiodo-4-nitrophenyl acetate and 2,6-diiodo-4-nitroanisole: Interplay of hydrogen bonds, iodo-nitro interactions and aromatic π-π-stacking interactions to give supramolecular structures in one, two and three dimensions
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In 2,6-diiodo-4-nitrophenol, C6H3I2NO3, the molecules are linked, by an O-H...O hydrogen bond and two iodo-nitro interactions, into sheets, which are further linked into a three-dimensional framework by aromatic π-π-stacking interactions. The molecules of 2,6-diiodo-4-nitrophenyl acetate, C8H5I2NO4, lie across a mirror plane in space group Pnma, with the acetyl group on the mirror, and they are linked by a single iodo-nitro interaction to form isolated sheets. The molecules of 2,6-diiodo-4-nitroanisole, C7H5I2NO3, are linked into isolated chains by a single two-centre iodo-nitro interaction.
- Garden, Simon J.,Da Cunha, Fernanda R.,Wardell, James L.,Skakle, Janet M.S.,Low, John N.,Glidewell, Christopher
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p. o463-o466
(2007/10/03)
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- Multinuclear Magnetic Resonance Spectroscopic and Semiempirical Molecular Orbital (AM1) Studies of Substituted Anisoles
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13C, 15N, and 17O NMR spectra have been recorded for 4-nitroanisole (1), its 2-methyl-, 2-chloro-, 2-bromo-, 2-iodo-, 2,6-diamethyl-, 2,6-dichloro, 2,6-dibromo-, and 2,6-diiodo-derivatives 2-9, also nitrobenzene (1a), its 3-methyl-, 3-chloro-, 3-bromo-, and 3-iodo-derivatives 2a-5a and 3,5-dichloro- and 3,5-dibromo-derivatives 7a and 8a.Analysis of the chemical shifts of carbon bearing nitro group and nitro oxygens in these compounds suggests that presence of one substituent ortho- to the methoxyl group enhances its resonance interaction with the benzene ring whereas presence of two ortho-substituents inhibits this resonance.However, in no case the resonance is completely inhibited.The extent of enhancement or inhibition is almost independent of the nature of the ortho-substituent.This conclusion has also been arrived by analyzing the reported chemical shifts of the para-carbons in anisoles 1b-9b and the corresponding carbons in benzene derivatives 1c-9c.Though evidence could not be obtained for steric enhancement of resonance using methoxyl oxygen chemical shifts, analysis of these chemical shifts in di-ortho-substituted anisoles 6-9 and 6a furnishes evidence for steric inhibition of resonance.However, 15N chemical shifts are of no use in studying these phenomena.Semiempirical molecular orbital calculations using AM1 Hamiltonian suggest that the methoxyl group is coplanar with the benzene ring in anisole, 4-nitroanisole and 2-substituted-4-nitroanisoles but is perpendicular to the benzene ring in 2,6-disubstituted-4-nitroanisoles.Moreover, in 2-substituted-4-nitroanisoles the O-methyl group is anti to the 2-substituent.
- Pandiarajan, Karuppiah,Kabilan, Senthamaraikannan,Sankar, Punnaivanam,Kolehmainen,Erkki,Nevalainen, Tapio,Kauppinen, Reijo
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p. 2639 - 2646
(2007/10/02)
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- Host-Guest Complexation. 50. Potassium and Sodium Ion-Selective Chromogenic Ionophores
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Making use of the principles of complementarity and preorganization, we have designed two potassium and one sodium ion-selective chromogenic ionophores useful for colorimetric assays of body and other fluids.Practical syntheses of 1-4 are described, and t
- Helgeson, Roger C.,Czech, Bronislaw P.,Chapoteau, Eddy,Gebauer, Carl R.,Kumar, Anand,Cram, Donald J.
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p. 6339 - 6350
(2007/10/02)
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