Electric linear dichroism and birefringence of biological polyelectrolytes

Charney, Elliot

doi:10.1017/s0033583500005011

Cited by 71 publications

(44 citation statements)

References 210 publications

(244 reference statements)

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“…bril component has the radially averaged B-DNA axis parallel to it and the (optically) uniaxial nature for unit cell, 12 are in accord, the chief polarizability of B-DNA being normal to the helix axis. 14 …”

Section: Discussionmentioning

confidence: 99%

“…type I (D-1501), a preparation prepared from calf The persistence length for random B-DNA dethymus gland (CT-DNA) and lyophilized from a termined in solution from a number of studies buffered solution by the manufacturer to yield a using light scattering and electric dichroism is apfibrous preparation which contains residual bufproximately 500 Å (or 150 base pairs) 14 but it fer salt and 5% NaCl. In vivo the molecular weight increases at low ionic strengths (10-20 mM) to should approach 2.8 billion g/mol for a DNA macca.…”

Section: Introductionmentioning

confidence: 99%

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The phase morphology and crystal growth habits of DNA fractions. Optical microscopy and light scattering

Monar

Phillips

1997

J. Polym. Sci. B Polym. Phys.

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Polydisperse DNA of reasonable molecular weights was prepared from a mammalian source via sonication and fractionation. A method for characterizing the molecular weight using gel electrophoresis is described. Quiescent crystallization was studied in thin films of one of the fractions induced by rapidly changing the hydration state isothermally. We report the occurrence of the semicrystalline nature of DNA. The crystal growth occurring via aggregates is best described as sheaves and spherulites from DNA gels in the relative humidity range (RH) corresponding to A‐DNA. These habits exhibit primary nucleation and secondary growth, which closely resemble those of melt‐crystallized, synthetic macromolecules and, in a follow‐up report, will be shown to be lamellar in nature. Small, needle‐like crystals are observed for B‐DNA hydration levels, and are unstable at lower hydration levels. A transformation from needle to lamellar crystals can occur, even when the primary nucleation of lamellar forms is otherwise absent at that hydration level, through a cylindrical phase exhibiting selective reflection of colored bands. The hydration level plays, in part, the role of the supercooling in this system and the long‐known hysteresis in the formation and dissolution of the A‐DNA (crystals) can now be viewed in light of those factors known to operate in semicrystalline systems. A morphological phase diagram is developed and is in accord with the known physical evidence. Because this preparation and these morphological observations are without precedence, substantial detail into methodology is included for this first article in the series. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1843–1854, 1997

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The phase morphology and crystal growth habits of DNA fractions. Optical microscopy and light scattering

Monar

Phillips

1997

J. Polym. Sci. B Polym. Phys.

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“…Experimental measurements indicated that the bases are oriented at 72" or less with respect to the helix axis direction (Charney, 1988). Moreover the larger ELD amplitude of the bound chromophores also arises from a local stiffening of the DNA around the intercalation sites (Herzyk et al, 1992).…”

Section: Intercalating Agentsmentioning

confidence: 99%

Drug—DNA sequence‐dependent interactions analysed by electric linear dichroism

Bailly

Hénichart

Colson

et al. 1992

J of Molecular Recognition

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The interactions between 20 drugs and a variety of synthetic DNA polymers and natural DNAs were studied by electric linear dichroism (ELD). All compounds tested, including several clinically used antitumour agents, are thought to exert their biological activities mainly by virtue of their abilities to bind to DNA. The selected drugs include intercalating agents with fused and unfused aromatic structures and several groove binders. To examine the role of base composition and base sequence in the binding of these drugs to DNA, ELD experiments were carried out with natural DNAs of widely differing base composition as well as with polynucleotides containing defined alternating and non-alternating repeating sequences, poly(dA).poly(dT), poly(dA-dT).poly(dA-dT),poly(dG).poly(dC) and poly(dG-dC).poly(dG-dC). Among intercalating agents, actinomycin D was found to be by far the most GC-selective. GC selectivity was also observed with an amsacrine-4-carboxamide derivative and to a lesser extent with methylene blue. In contrast, the binding of amsacrine and 9-aminoacridine was practically unaffected by varying the GC content of the DNAs. Ethidium bromide, proflavine, mitoxantrone, daunomycin and an ellipticine derivative were found to bind best to alternating purine-pyrimidine sequences regardless of their nature. ELD measurements provided evidence for non-specific intercalation of amiloride. A significant AT selectivity was observed with hycanthone and lucanthone. The triphenyl methane dye methyl green was found to exhibit positive and negative dichroism signals at AT and GC sites, respectively, showing that the mode of binding of a drug can change markedly with the DNA base composition. Among minor groove binders, the N-methylpyrrole carboxamide-containing antibiotics netropsin and distamycin bound to DNA with very pronounced AT specificity, as expected. More interestingly the dye Hoechst 33258, berenil and a thiazole-containing lexitropsin elicited negative reduced dichroism in the presence of GC-rich DNA which is totally inconsistent with a groove binding process. We postulate that these three drugs share with the trypanocide 4',6-diamidino-2-phenylindole (DAPI) the property of intercalating at GC-rich sites and binding to the minor groove of DNA at other sites. Replacement of guanines by inosines (i.e., removal of the protruding exocyclic C-2 amino group of guanine) restored minor groove binding of DAPI, Hoechst 33258 and berenil. Thus there are several cases where the mode of binding to DNA is directly dependent on the base composition of the polymer. Consequently the ELD technique appears uniquely valuable as a means of investigating the possibility of sequence-dependent recognition of DNA by drugs.

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“…Equation [11] shows that the relaxation time τ 1 is very sensitive to the diameter (2b) of a thin disklike particle of a fixed thickness of 2a. For example, a 1.5-fold increase of the diameter corresponds to a 3.37-fold increase in the relaxation time.…”

Section: Decay Signal and Field-off Relaxation Timementioning

confidence: 99%