(1) However, at a 50-fold higher strand concentration, the single-stranded oligomer is gradually converted into the quadruplex.
(2) We propose a model in which duplex or hairpin forms of G-DNA are folding intermediates in the formation of either 1-, 2-, or 4-stranded quadruplex structures.
(3) There has been much recent interest in the self-association of short deoxyguanosine-rich motifs within single-stranded DNAs to generate monovalent cation modulated four-stranded helical segments called G-quadruplexes stabilized by hydrogen-bonded G-tetrad alignments.
(4) Thus the number of T residues surrounding the dG cluster might control the rigidity of the quadruplex structure.
(5) Equilibrium ultracentrifugation studies confirm that these quadruplexes are composed of two strands of d(G3T4G3).
(6) The only precedent known (to us) for a cation-specific stabilization is that seen in the quadruplex structure formed by poly I.
(7) The quadruplex, [d(TTGGGGTT)]4, is resistant to denaturation in 7 M urea, in which the Watson-Crick type d(TTGGGGTT).d(AACCCCAA) duplex dissociates.
(8) We observe well-resolved proton NMR spectra corresponding to a G-quadruplex monomer conformation predominant at 50 mM K cation concentration and a G-quadruplex dimer conformation predominant at 300 mM K cation concentration.
(9) Our results indicate that specific differences in ionic interactions can result in a switch in telomeric DNAs between intramolecular hairpin-like or quadruplex-containing species and intermolecular quadruplex structures, all of which involve G.G base pairing interactions.
(10) The possible biological function of quadruplexes is discussed.
(11) The DNA oligonucleotide d(CGCG3GCG) can form either a Watson-Crick (WC) hairpin or a parallel-stranded quadruplex structure containing six G-quartet base pair assemblies.
(12) We find that these molecules fold to form a symmetrical bimolecular and an intramolecular quadruplex, respectively.
(13) An increase in ionic strength stabilizes the single-stranded structure, so it seems to inhibit the formation of the quadruplex.
(14) Experiments on ethidium bromide binding to the oligonucleotides have shown that the oligomer anti(A-T) exists, at a low ionic strength, as a four stranded complex ("quadruplex") contains two antiparallel helices, d(A).d(T), which have a parallel orientation and are bound to one another owing to the formation of additional hydrogen bonds between nucleic acid bases.
(15) The quadruplex is stable in the presence of 40 mM K+ at micromolar DNA concentration and can be kinetically trapped as a metastable form when prepared at millimolar DNA concentration and then diluted into buffer containing 40 mM Na+.
(16) Cations stabilize the quadruplex in the order K+ greater than Ca2+ greater than Na+ greater than Mg2+ greater than Li+ and K+ greater than Rb+ greater than Cs+, indicating that K+ has an optimum ionic radius for complex formation and that ionic charge affects the extent of ion-induced stabilization.
(17) Comparison with the corresponding CD spectral characteristics suggests that the electrophoretic intensity enhancement of the intermolecular G-quadruplex band is correlated to the intensity enhancement of of the positive CD maximum at 265 nm.
(18) Similar but less dramatic enhancement of the intermolecular quadruplex band is also observed in T4.
(19) Since K+ and NH4+ are known to stabilize a parallel-stranded quadruplex structure of poly[r(I)4], we infer that the multistranded structure is a quadruplex.
(20) UV thermal denaturation curves show a single concentration-dependent transition and provide data for quantitating the thermodynamics of quadruplex formation.
Reproduce
Definition:
(v. t.) To produce again.
(v. t.) To bring forward again; as, to reproduce a witness; to reproduce charges; to reproduce a play.
(v. t.) To cause to exist again.
(v. t.) To produce again, by generation or the like; to cause the existence of (something of the same class, kind, or nature as another thing); to generate or beget, as offspring; as, to reproduce a rose; some animals are reproduced by gemmation.
(v. t.) To make an image or other representation of; to portray; to cause to exist in the memory or imagination; to make a copy of; as, to reproduce a person's features in marble, or on canvas; to reproduce a design.
Example Sentences:
(1) Results by these three assays were also highly reproducible.
(2) Pokeweed mitogen-stimulated rat spleen cells were identified as a reliable source of rat burst-promoting activity (PBA), which permitted development of a reproducible assay for rat bone marrow erythroid burst-forming units (BFU-E).
(3) In experiments performed to determine whether PtdIns(4,5)P2 hydrolysis induced by TRH may have been caused by the elevation of [Ca2+]i, the following results were obtained: the effect of TRH to decrease the level of PtdIns(4,5)P2 was not reproduced by the calcium ionophore A23187 or by membrane depolarization with 50 mM K+; the calcium antagonist TMB-8 did not inhibit the TRH-induced decrease in PtdIns(4,5)P2; and, most importantly, inhibition by EGTA of the elevation of [Ca2+]i did not inhibit the TRH-induced decrease in PtdIns(4,5)P2.
(4) The tilt was reproduced with a typical spread of about 10 degrees.
(5) The reproducibility of the killing-curve method suggests that at least two different concentrations should be used and that a decrease in viable counts below 2 log10 after 24 hours does not exclude a synergistic action.
(6) Hyperimmunization with the tick encephalitis and Western horse encephalomyelitis viruses reproduced in the brain of albino mice, intensified the protein synthesis in the splenic tissue during the productive phase of the immunogenesis (the 7th day).
(7) The schedule proposed is easy to use and reproducible.
(8) An accurate and reproducible method is described for generating a map of the cobalt sheet source from images of it made in multiple positions with the scintillation camera.
(9) These studies establish this preparation as a reproducible model for the direct examination of autonomic influences on endocrine pancreatic function.
(10) REA is stable, sensitive, accurate and reproducible.
(11) Taken together, these data indicate that the regulation of probing angulation in clinical measurement of GAL with the TAPP is an important determinant of the reproducibility of periodontal probing.
(12) We did three repeated PD measures of mean aortic flow velocity in ten term infants (using four trained operators) to determine inter- and intraoperator reproducibility.
(13) The interobserver variability of these indices is low (r greater than 0.96); reproducibility is good in patients with sinus rhythm but mediocre in atrial fibrillation.
(14) The results of this study demonstrate that the increases in triacylglycerol synthesis and the cytosolic activity of phosphatidate phosphohydrolase previously observed by us in the ketotic diabetic liver, could be reproduced in normal fed rat liver cells by incubating them with acetoacetate.
(15) The method of mineral estimation using phalanges is described and its reproducibility was tested on 17 parameters.
(16) The temperature-activated 4 to 5 S EBP transformation is found to be highly reproducible without loss of [3H]estradiol-binding activity in a buffer containing an excess of [3H]estradiol, 40 mM Tris, 1 mM dithiothreitol, and 1 M urea at pH 7.4.
(17) Most of the subjects' mandibular movements did not improve to the point of making reproducible border movements on a pantograph.
(18) The reproducibility of heart rate variability indices was not improved by orthostatic or ergometric challenge.
(19) The reproducibility was 0.5% and the correlation with the ID-MF technique was 0.997.
(20) The assay of cytochrome P-450 in liver homogenate is accurate enough to calculate a reproducible recovery factor.