scholarly journals New G-Quadruplex-Forming Oligodeoxynucleotides Incorporating a Bifunctional Double-Ended Linker (DEL): Effects of DEL Size and ODNs Orientation on the Topology, Stability, and Molecularity of DEL-G-Quadruplexes

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 654 ◽  
Author(s):  
Maria Marzano ◽  
Andrea Falanga ◽  
Stefano D’Errico ◽  
Brunella Pinto ◽  
Giovanni Roviello ◽  
...  
Keyword(s):  
Size Exclusion Chromatography ◽  
Structural Characterization ◽  
Size Exclusion ◽  
Biological Processes ◽  
Dna Nanostructures ◽  
Nmr Studies ◽  
Molecular Weights ◽  
G Quadruplex ◽  
Exclusion Chromatography

G-quadruplexes (G4s) are unusual secondary structures of DNA occurring in guanosine-rich oligodeoxynucleotide (ODN) strands that are extensively studied for their relevance to the biological processes in which they are involved. In this study, we report the synthesis of a new kind of G4-forming molecule named double-ended-linker ODN (DEL-ODN), in which two TG4T strands are attached to the two ends of symmetric, non-nucleotide linkers. Four DEL-ODNs differing for the incorporation of either a short or long linker and the directionality of the TG4T strands were synthesized, and their ability to form G4 structures and/or multimeric species was investigated by PAGE, HPLC–size-exclusion chromatography (HPLC–SEC), circular dichroism (CD), and NMR studies in comparison with the previously reported monomeric tetra-ended-linker (TEL) analogues and with the corresponding tetramolecular species (TG4T)4. The structural characterization of DEL-ODNs confirmed the formation of stable, bimolecular DEL-G4s for all DEL-ODNs, as well as of additional DEL-G4 multimers with higher molecular weights, thus suggesting a way towards the obtainment of thermally stable DNA nanostructures based on reticulated DEL-G4s.

Characterization of polyamides 6, 11, and 12. Determination of molecular weight by size exclusion chromatography (IUPAC Technical Report)

2004 ◽  
Vol 76 (11) ◽  
pp. 2009-2025 ◽  
Author(s):  
E. C. Robert ◽  
Rudolf Bruessau ◽  
J.-E. Dubois ◽  
Bernard Jacques ◽  
Nico Meijerink ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
Working Party ◽  
Size Exclusion ◽  
Molecular Weights ◽  
Relative Standard ◽  
Exclusion Chromatography ◽  
Iupac Commission ◽  
Commercial Polymers

This report presents the results from IUPAC Working Party IV.2.2 of the global trial within the framework of IUPAC Commission IV.2, “Characterization of Commercial Polymers”. The results were compared on the basis of molecular weight obtained by size exclusion chromatography (SEC)using different techniques practiced in participating laboratories, the majority of which were materials suppliers. The practical methodologies used different solvents for the polymers, in particular, benzyl alcohol, 1,1,1,3,3,3 hexafluoropropan-2-ol and tetrahydrofuran; the latter solvent was used after chemical modification of the polyamides, in general with trifluoroacetic anhydride. Eight laboratories participated in the trial. The repeatability for molecular weight in each laboratory was good, whatever technique was used, the relative standard deviation averaged over all laboratories being around 3%. The deviations in distribution of molecular weights with different experimental methodologies were broader, but were reasonably good despite the diversity of methods. The differences in the distribution correspond to a confidence interval of about 30% in molecular weight.

Molecular Weight Characterization of Food Grade Polyethylenes and Extractables by Size Exclusion Chromatography

1981 ◽  
Vol 64 (4) ◽  
pp. 1008-1013
Author(s):  
Roger C Snyder ◽  
Charles V Breder
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
High Density ◽  
Size Exclusion ◽  
Low Density ◽  
Food Grade ◽  
Molecular Weights ◽  
Exclusion Chromatography ◽  
Band Spreading

Abstract Size exclusion chromatography (SEC) was used to characterize the molecular weight distribution (MWD) of 6 low density and 6 high density food grade polyethylene resins. The hexane and xylene extractable fractions of these 12 resins were also analyzed by SEC. An IBM 370/168 computer with an APL program was used to analyze the chromatograms and correct for chromatographic band spreading and skewing. Calculated weight average molecular weights (Mw) for the resins ranged from 40 000 to 200 000 and number average molecular weights (Mn) ranged from 6000 to 60 000. Median values of Mw and Mn were 1800 and 950, respectively, for hexane extractables from the low density resins, and were 310 and 290, respectively, for hexane extractables from the high density resins. Corresponding Mw and Mn values for xylene extractables were consistently larger than those for hexane extractables.

Structural characterization of products from fuel-rich combustion: An approach based on size exclusion chromatography

2002 ◽  
Vol 174 (11-12) ◽  
pp. 345-359 ◽  
Author(s):  
B. Apicella ◽  
A. Ciajolo ◽  
I. Suelves ◽  
T. J. Morgan ◽  
A. A. Herod ◽  
...  
Keyword(s):  
Size Exclusion Chromatography ◽  
Structural Characterization ◽  
Size Exclusion ◽  
Exclusion Chromatography

Synthesis and characterization of new, liquid, branched poly(methylvinylborosiloxanes)

e-Polymers ◽  
2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Jerzy Chruściel ◽  
Marzena Fejdyś ◽  
Witold Fortuniak
Keyword(s):  
Functional Groups ◽  
Atomic Spectroscopy ◽  
Size Exclusion ◽  
Random Structure ◽  
Molecular Weights ◽  
Chemical Structures ◽  
Siloxane Oligomers ◽  
Exclusion Chromatography ◽  
Ether Solution

Abstract New liquid branched poly(methylvinylborosiloxanes) (br-PMVBS) of random structure were synthesized in three steps. By reacting boric acid with an excess of dimethyldichlorosilane (Me2SiCl2) in dry ether a “borosiloxane precursor”: tris(chlorodimethylsilyl) borate B(OSiMe2Cl)3 was prepared. In the second step of synthesis ether solution of B(OSiMe2Cl)3 was added to a mixture of appropriate organic chlorosilanes (Me2SiCl2, MeViSiCl2, MeSiCl3, and Me3SiCl) and all reagents were reacted with stoichiometric amounts of water, in the presence of pyridine (as an acceptor of HCl), in dry ether, at low temperature (usually at -10 to 0 C). In order to fully react (“to block”) trace silanol groups, reactions of intermediate PMVBS with additional batches of Me3SiCl were carried out in the third step, C5H5N·HCl was filtered off and washed with a dry ether. The solvent was distilled off from filtrates and low molecular weight siloxane oligomers were removed by a vacuum distillation at 130-150 C. Chemical structures of br-PMVBS were confirmed by elemental analysis and spectroscopic methods (FTIR, emission atomic spectroscopy ICP-AES, and NMR: 1H, 29Si and 11B). On the basis of analysis of their 29Si-NMR spectra the microstructure of polysiloxane chains was proposed. The prepared br-PMVBS had in their structures: triple branching borosiloxane units: BO1.5 and in some cases methylsiloxane moiety CH3SiO1.5 (T). They contained linkages: Si-O-Si, Si-O-B, vinyl(methyl)siloxane functional groups (CH2=CH)MeSiO (Dvi), dimethylsiloxane mers (CH3)2SiO (D), and non-reactive trimethylsiloxy terminal groups (CH3)3SiO0.5 (M), but they did not have: hydroxyl functional groups: Si-OH and B-OH, and sensitive to water B-O-B linkages. Molecular weights of br-PMVBS (Mn = 1500-3300 g/mol; Mw = 3800-7400 g/mol) and their polydispersity (Mw/Mn = 2.0-2.5) were determined by a size exclusion chromatography (SEC).

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