Results 161 to 170 of about 11,463 (183)

Geometry and mechanics of DNA superhelicity

Biopolymers, 1983
AbstractThis paper analyzes the elastic equilibrium conformations of duplex DNA constrained by the constancy of its molecular linking number, Lk. The DNA is regarded as having the mechanical properties of a homogeneous, linearly elastic substance with symmetric cross section.
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Superhelicity and DNA Radiation Sensitivity

SAE Technical Paper Series, 1990
<div class="htmlview paragraph">Several underwound families of topoisomers of the plasmid pIB130 were irradiated with fission neutrons at 28 C in TE buffer. Form I DNA followed the expected exponential dependence on dose, and was greater for those DNA molecules characterized by larger linking numbers.
Charles E. Swenberg, Eric A. Holwitt, James M. Speicher   +2 more
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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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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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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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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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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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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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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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