Showing papers in "Acta Chemica Scandinavica in 1993"
187 citations
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TL;DR: There exists a sequence-selective metal ion binding pattern that binds predominantly to 5'-G in the contexts 5'-GC and 5'-GA, and the order of preference seems to be GG > or = GA > GT > > GC.
Abstract: Metal ion titrations of several DNA oligonucleotides, 10 dodecamers and one decamer have been monitored by 1H NMR spectroscopy in order to elucidate metal ion binding patterns. Also, the effects of paramagnetic impurities on resonance linewidths and NOESY cross-peak intensities have been reversed by EDTA back-titration experiments. 1H 1D NMR spectra were recorded after successive additions of aliquots of different metal salts to oligonucleotide samples. Paramagnetic manganese(II) salts were used in most cases, but a few samples were also titrated with diamagnetic zinc(II). From this study, we conclude that there exists a sequence-selective metal ion binding pattern. The metal ions bind predominantly to 5'-G in the contexts 5'-GC and 5'-GA. The order of preference seems to be GG > or = GA > GT > > GC. No evidence of metal ion binding to 5'-G in 5'-GC steps or to non-G residues was found. The H6 or H8 resonances on preceding (5'-) bases were affected by the adjacent bound paramagnetic metal ion, but no effect was observed on the protons of the succeeding (3'-) base. The metal binding site in the duplexes is most likely at G-N7, as manifested by the pronounced paramagnetic line broadening or diamagnetic shift of the G-H8 signal. This sequence selectivity may be qualitatively explained by a sequence-dependent variation in the molecular electrostatic potentials of guanine residues (MEPs) along the oligonucleotide chain.
65 citations
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TL;DR: None of the compounds were found to have antiviral effect against herpes simplex type 2 (HSV-2), human immunodeficiency (HIV), and cytomegalovirus in doses not toxic to the cells.
Abstract: 4-Azido, 4-amino, 4-amido and 4-alkoxy compounds related to the lignans podophyllotoxin and 4'-demethylepipodophyllotoxin have been synthesized, and their structures elucidated. The Ritter reaction was shown to be useful in the preparation of the 4-amido compounds with the required stereochemistry. A preparative method for 4-chloro-4-deoxypicrophyllotoxin, for which all earlier synthetic attempts resulted in the two dehydrated compounds, alpha- and beta-apopicropodophyllotoxin, was developed. Supplementary preliminary studies of the biological activities of some of the compounds were performed. All compounds had pronounced inhibitory effect on the in vitro growth of human cervical cancer cells and TC-mouse cells with 4-amino-4-deoxypodophyllotoxin and 4-azido-4-deoxypodophyllotoxin showing the highest activity. Alkaline elution studies indicate that the toxicity of the 4'-demethoxy derivatives is due to protein-mediated DNA nicking. None of the compounds were found to have antiviral effect against herpes simplex type 2 (HSV-2), human immunodeficiency (HIV), and cytomegalovirus (CMV) in doses not toxic to the cells.
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39 citations
TL;DR: When equal amounts of dipicolinic (pyridine-2,6-dicarboxylic) acid and zinc sulfate were incubated at 277K, two different zinc dipicolinate compounds of composition Zn 2 (C 7 H 3 NO 4 ) 2.7H 2 O and Zn(C 7H 4 NO 4 ), 2.3H2 O were formed as mentioned in this paper.
Abstract: When equal amounts of dipicolinic (pyridine-2,6-dicarboxylic) acid and zinc sulfate were incubated at 277K, two different zinc dipicolinate compounds of composition Zn 2 (C 7 H 3 NO 4 ) 2 .7H 2 O and Zn(C 7 H 4 NO 4 ) 2 .3H 2 O were formed. In both compounds the coordination polyhedra are distoted octahedra with Zn-N=2.003-2.016A and Zn-O=2.078-2.349A. The compounds crystallize in the monoclinic space group P2 1 /c with four formula units in the unit cell.
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TL;DR: In this article, the palladium-catalyzed arylation of vinyl ethers with nitrogen-containing directing groups has been studied, including Ethenyloxyalkylamines 1a-c and pyridines 2a-d.
Abstract: Chelation-controlled, palladium-catalyzed arylation of vinyl ethers with nitrogen-containing directing groups has been studied. Ethenyloxyalkylamines 1a-c and pyridines 2a-d, representing different ...
TL;DR: In this paper, the title compound has been shown to have a composite structure consisting of two interpenetrating, modulated sublattices, one consisting of a sandwich and the other consisting of CuO 2 ribbons extending along the c-axis.
Abstract: The title compound has been shown to have a composite structure consisting of two interpenetrating, modulated sublattices. One substructure is a sandwich. Adjacent layers are Cu 2 O 3 sheets extending in the ac-plane, and Bi, Sr, and Ca atoms, which are statistically distributed over one atomic site. The other substructure is interleaved between the layers of metal atoms and consists of CuO 2 ribbons extending along the c-axis. Both substructures are orthorhombic, with the same a- and b-axis values, which accounts for the modulation
TL;DR: In this article, the cis and trans compounds of the P2 1 /n space group were crystallized in the space group Pbca with a=10614, b=11283, c=11015A, β=9333°, Z=4 The refinement converged to R=0057.
Abstract: The cis compound crystallizes in the space group P2 1 /n with a=10614, b=11283, c=11015A, β=9333°, Z=4 The refinement converged to R=0057 The trans compound crystallizes in Pbca with a=7959, b=8972, c=18590A, Z=4 The refinement converged to R=0031 The coordination geometry is sqaure-planar in both compounds In the cis compound the Pt-Cl distances are in the range 2321-2327A and the Pt-S distances are both 2273A In the trans compound the Pt-Cl and Pt-S distances are 2300 and 2298A