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- Eriksson, Maja, 1975, et al.
(author)
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Comparing mono- and divalent DNA groove binding cyanine dyes--Binding geometries, dissociation rates, and fluorescence properties
- 2006
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In: Biophysical Chemistry. - : Elsevier BV. - 1873-4200 .- 0301-4622. ; 122:3, s. 195-205
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Journal article (peer-reviewed)abstract
- The unsymmetrical cyanine dyes BOXTO-PRO and BOXTO-MEE were derived from the DNA groove binder BOXTO, by adding a positively charged or a non-ionic hydrophilic tail to BOXTO, respectively. The main objective was to obtain more efficient DNA probes, for instance in electrophoresis and microscopy, by slowing down the dissociation of BOXTO from DNA. The interactions with mixed sequence DNA was studied with fluorescence and absorbance spectroscopy, stopped-flow dissociation and gel electrophoresis. Both the derivatives are groove bound as BOXTO, and have similar fluorescence properties when bound to mixed sequence DNA in free solution. BOXTO-PRO exhibits a slower dissociation than BOXTO from DNA, whereas the dissociation rate for BOXTO-MEE is faster and, unexpectedly independent of the ionic strength. During gel electrophoresis both BOXTO-PRO and BOXTO-MEE exhibit a faster dissociation rate than BOXTO. Still, BOXTO-PRO seems to be a good alternative as DNA probe, especially for applications in free solution where the dissociation is slower than for the corresponding intercalator TOPRO-1.
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- Eriksson, M., et al.
(author)
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Time-resolved electrophoretic analysis of mobility shifts for dissociating DNA ligands
- 2005
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In: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 26:3, s. 524-532
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Journal article (peer-reviewed)abstract
- Intercalative binding of ligands to DNA can be demonstrated by helix unwinding, monitored by gel electrophoresis of supercoiled DNA, as electrophoretic mobility is sensitive to the topological DNA state. However, we show that an apparent lack of unwinding in an electrophoretic assay could be due to dissociation of the (intercalated) ligand during the analysis, rather than evidence for a nonintercalative mode of binding to DNA. Repetitive scanning during the electrophoresis ensures that release of the ligand during electrophoresis does not affect the measured degree of unwinding, based on the electrophoretic velocity being determined as a function of time. We use this assay to establish intercalation as a mode of binding to DNA for the cyanine dyes YO, YO-PRO as well as two enantiomeric forms of the ruthenium complexes [(phen)2 Ru(tatpp)Ru(phen)2]4+, and to support groove-binding for the new unsymmetrical cyanine dyes BOXTO and BOXTO-PRO. Groove-binding could be concluded from a lack of unwinding, because we could rule out that it is caused by release of the dye during the electrophoresis. The gel electrophoresis has the advantage over hydrodynamic techniques that much smaller sample amounts are required, and our time-resolved approach can be employed in all mobility-shift assays when applied to dissociating complexes.
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- Hasani, Merima, 1978, et al.
(author)
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Cationization of Cellulose by Using N-Oxiranylmethyl-N-Methylmorpholinium Chloride and 2-Oxiranylpyridine as Etherification Agents
- 2009
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In: Journal of Applied Polymer Science. - : Wiley. - 1097-4628 .- 0021-8995. ; 114:3, s. 1449-1456
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Journal article (peer-reviewed)abstract
- Cationization of cellulose under aqueous alkaline conditions was studied. Two new epoxy reagents, N-oxiranylmethyl-N-methylmorpolinitim chloride and 2-oxiranylpyridine, were used for preparation of cationic cellulose ethers. Using the first agent, cationic ethers were obtained in one step, whereas the latter one yielded a reactive intermediate used as a precursor for two different cationizations. Etherification with the commonly used 2,3-epoxypropyltrimethylammonium chloride was also performed and used as a reference reaction. By changing water content in the reaction mixture two groups cellulose ethers with different degrees of cationization were prepared. As expected, reducing the water content resulted in a higher degree of etherification and hence a more pronounced cationic character of the obtained ethers. Characterization by FTIR, elemental- and gravimetric analysis confirmed the formation of the desired ethers. Their ability to interact with water and adsorb the acid dye, methyl orange, was also studied, confirming further introduction of the cationic substituents and revealing different reactivities of the used epoxy reagents. From characterization, it could be concluded that N-oxiranylmethyl-N-methylmorpholinium chloride exhibits higher reactivity toward cellulose than both the reference compounds and 2-oxiranylpyridine. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 1449-1456, 2009
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- Hasani, Merima, 1978, et al.
(author)
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New coupling reagents for homogeneous esterification of cellulose
- 2007
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In: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 14:4, s. 347-356
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Journal article (peer-reviewed)abstract
- A group of known, but in cellulose chemistry new coupling reagents for homogeneous esterification has been investigated: 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methyl-morpholinium chloride, N-methyl-2-bromopyridinium iodide, N-methyl-2-chloropyridinium iodide, and N-methyl-2-bromopyridinium tosylate. In order to study their ability to activate carboxylic acids in esterifications of cellulose they have been employed in synthesis of cellulose adamantate esters. Their effectiveness has been estimated in terms of degree of substitution of resulting esters and compared to that obtained with the commonly used N,N'-carbonyldiimidazole.
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- Ishihara, M., et al.
(author)
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Quantitative structure-cytotoxicity relationship analysis of phenoxazine derivatives by semiempirical molecular-orbital method
- 2007
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In: Anticancer Research. - 0250-7005 .- 1791-7530. ; 27:6B, s. 4053-4057
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Journal article (peer-reviewed)abstract
- A semiempirical molecular-orbital method (CAChe) was applied to delineate the relationship between the cytotoxicity (evaluated by 50% cytotoxic concentration, CC50) of fifteen phenoxazine derivatives and eleven physical parameters (descriptors). Most of the phenoxazine derivatives had extended and planar structure. The cytotoxic activity of phenoxazines against the human oral squamous cell carcinoma HSC-2 and HSC-4 cells correlated to electron affinity, absolute hardness (eta), absolute electron negativity (chi) and octanol-water distribution coefficient (log-P). However, only log-P was correlated to CC50 in the HSC-3 cells, whereas only heat of formation and log-P were correlated to CC50 in the human promyelocytic leukemia HL-60 cells. The cytotoxic activity of the phenoxazine derivatives became maximum at the log-P=5.9. Their cytotoxicity strongly depended on the chi value, but not on the eta value. Compounds with relatively higher cytotoxicity showed higher chi value (chi > 5.28), whereas compounds with relatively lower cytotoxicity showed lower chi value (chi < 4.27). These data suggest that appropriate chemical descriptors should be selected to estimate the cytotoxicity of phenoxazines, depending on the target cells.
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