Results 181 to 190 of about 7,436 (214)

Alteration of superhelical state of DNA by aluminium (Al)

Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression, 1993
The effect of aluminium (Al) on the supercoiled state of pUC18 DNA was studied by ethidium bromide fluorescence and agarose gel electrophoresis. Al at physiologically relevant concentrations relaxed the intact supercoiled DNA as well as the topoisomers induced by chloroquine. EDTA prevented the unwinding effect of Al on supercoiled DNA.
K S, Rao, B S, Rao, D, Vishnuvardhan, K V, Prasad   +3 more
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Electron microscopy of superhelical circular λ DNA

Journal of Molecular Biology, 1968
Abstract Electron microscopy confirms that circular λ DNA molecules contain supertwists. The average number of primary supertwists at low ionic strength (0.06) is 117, or 3.8 per million molecular weight. This number is not constant but decreases to an average of 12 when the ionic strength is increased to 2.0.
V C, Bode, L A, MacHattie
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Theory of DNA Superhelicity

1985
When a duplex DNA molecule is covalently closed into a circle, conservation of the antiparallel chemical (5′–3′) orientations of the two strands dictates that the resulting ring molecule must have the topological structure of two closed, interlinked circles. This fixes the value of the molecular linking number Lk.
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Thermostability and superhelicity of plasmid DNA in Bacillus stearothermophilus

Molecular and General Genetics MGG, 1987
The thermostability of the staphylococcal plasmids pC194 and pUB110 and their antibiotic-resistance determinants was examined upon transfer to Bacillus stearothermophilus CU21. Plasmid pGS13, a pUB110 derivative carrying the chloramphenicol acetyltransferase (CAT) gene of pC194, could be maintained up to the maximum growth temperature (68 degrees C) by
E, Soutschek-Bauer, W, Scholz, E, Grill, W L, Staudenbauer   +3 more
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Thermodynamics of the B–Z transition in superhelical DNA

Nature, 1984
One of the most exciting events in recent years in molecular biology was the discovery of the left-handed Z form of the DNA double helix. Originally found in linear self-complementary d(GC)x . d(GC)x polymers and oligomers in non-physiological conditions (a rather high salt concentration), it was recently shown to be easily enough adopted in ...
M D, Frank-Kamenetskii, A V, Vologodskii
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Superhelical Escherichia coli DNA: Relaxation by coumermycin

Journal of Molecular Biology, 1978
Abstract Folded chromosomes isolated from Escherichia coli strains after treatment with coumermycin A 1 in vivo , an inhibitor of DNA gyrase (Gellert et al. , 1976 a,b ), were found to have reduced DNA superhelical densities. This loss of DNA supercoiling paralleled inhibition of DNA synthesis.
K, Drlica, M, Snyder
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Structures of Homopurine-homopyrimidine Tract in Superhelical DNA

Journal of Biomolecular Structure and Dynamics, 1986
For homopurine-homopyrimidine tracts in superhelical DNA, we propose a structure involving Watson-Crick and Hoogsteen paired triple helixes, hairpin loops and unstructured domains. Topologically, the whole structure is equivalent to an open region. The proposed structure is consistent with available S1 cleavage, pH and alkylation data and energetics ...
V I, Lyamichev, S M, Mirkin, M D, Frank-Kamenetskii   +2 more
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Attachment of nascent RNA molecules to superhelical DNA

Journal of Molecular Biology, 1975
Comparisons are made of the attachment of nascent RNA molecules synthesized in vitro with Escherichia coli RNA polymerase on native bacteriophage PM2 DNA, a double-helical circular DNA with −110 superhelical twists, and on a derivative of this DNA with no superhelical twists.
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Superhelical model of DNA for regulation of gene expression

Journal of Theoretical Biology, 1983
A superhelical higher-order structure is proposed as a model of template DNA for regulation of transcription in simian virus 40. A stem-and-loop structure is located 3' downstream from the transcriptional initiation site in the sense strand. The complementary sequences to the loop regions in both strands are found between the 70th and the 300th ...
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Energetics of the strand separation transition in superhelical DNA

Journal of Molecular Biology, 1992
In this paper the values of three free energy parameters governing the superhelical strand separation transition are determined by analysis of available experimental data. These are the free energy, a, needed to initiate a run of separation, the torsional stiffness, C, associated with interstrand winding of the two single strands comprising a separated
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