Understanding DNA structure and packing in crystals.
Item
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Title
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Understanding DNA structure and packing in crystals.
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Identifier
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AAI9405512
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identifier
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9405512
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Creator
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Chen, Shun-Le.
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Contributor
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Adviser: Gary Joseph Quigley
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Date
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1993
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Biochemistry | Chemistry, Physical
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Abstract
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Three structures of DNA oligomers and DNA-drug complex have been examined, using X-ray diffraction method.;The high resolution low temperature structure of Z-DNA, d(CGCGCG){dollar}\sb2{dollar} shows a dual conformation. At GpC steps of the oligomer, the phosphate group can assume either a ZI or ZII conformation. The relative probabilities of the two conformations are determined to be 75/25 percent for phosphate P3 and 85/15 percent for phosphate P9. The counterion, Mg(II), in the crystal structure shows a strong conformational and crystallographic packing dependency. Some Mg(II) are partially occupied. The magnesium-water complex dimmer has been determined to be 75 percent occupancy. The structure of DNA and solvent shows highly anisotropic thermal motion.;The structure of copper(II)-Z-DNA complex shows a strong base-specific interaction. Not only do the guanine bases interact with copper(II) ion, but also the adenine bases, which are in a particular crystallographic environment, can interact with the copper(II) ion strongly. The geometry of copper-solvent complexes can be octahedral or trigonal bipyramidal. All of copper(II) ions are partially occupied.;Ditercalinium bis-intercalates into d(CGCG){dollar}\sb2{dollar} at the two CpG steps. The intercalation causes helical unwinding, widening of the minor groove, and a 15{dollar}\sp\circ{dollar} kink on the DNA oligomer. These structural variations might be recognized by the uvrABC proteins, and be the trigger of DNA repair machinery.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
