Ultraviolet circular dichroism studies on synthetic polynucleotides

1969 ◽  
Vol 47 (6) ◽  
pp. 637-642 ◽  
Author(s):  
Fred H. Wolfe ◽  
Kimio Oikawa ◽  
Cyril M. Kay
Keyword(s):  
Circular Dichroism ◽  
Wavelength Region ◽  
Ph Values ◽  
Polycytidylic Acid ◽  
Naturally Occurring ◽  
Polyinosinic Acid ◽  
Polyadenylic Acid ◽  
Polyuridylic Acid ◽  
Extreme Sensitivity ◽  
Circular Dichroïsm

The ultraviolet circular dichroism spectra of polyadenylic acid, polyguanylic acid, polycytidylic acid, polyinosinic acid, and polyuridylic acid have been examined at neutral and acidic pH values, and at moderate and low ionic strengths, over the wavelength range 300–185 mμ. Increased resolution of spectra below 225 mμ has revealed heretofore unexamined ellipticity bands in the low wavelength region, which are sensitive to conformational alterations for those polynucleotides which exhibit both single and multistranded secondary structures. It is concluded that these ellipticity bands, in view of their extreme sensitivity to conformation, will be of significance in increasing the usefulness of the homopolynucleotides as model compounds in conformational studies of naturally occurring RNAs.

Ultraviolet circular dichroism studies on complexes of synthetic polynucleotides

1969 ◽  
Vol 47 (10) ◽  
pp. 977-981 ◽  
Author(s):  
Fred H. Wolfe ◽  
Kimio Oikawa ◽  
Cyril M. Kay
Keyword(s):  
Circular Dichroism ◽  
Wavelength Range ◽  
Optically Active ◽  
Electronic Transitions ◽  
Molar Ratio ◽  
Circular Dichroism Spectra ◽  
Naturally Occurring ◽  
Polyadenylic Acid ◽  
Polyuridylic Acid ◽  
Circular Dichroïsm

The ultraviolet circular dichroism spectra of complexes of polyadenylic acid and polyuridylic acid in the molar ratio of 1:1 and 1:2, and that of polyguanylic acid and polycytidilic acid have been examined over the wavelength range of 300–185 mμ. Increased resolution of spectra below 225 mμ has revealed several new ellipticity bands for these complexes which should be of considerable value in the proper counting of optically active electronic transitions and their assignment in these systems, and with naturally occurring RNA's.

scholarly journals The interaction of aflatoxin B1 with polynucleotides and its effect on ribonucleic acid polymerase

1969 ◽  
Vol 114 (4) ◽  
pp. 679-687 ◽  
Author(s):  
A. M. Q. King ◽  
B. H. Nicholson
Keyword(s):  
Ionic Strength ◽  
Aflatoxin B1 ◽  
Polycytidylic Acid ◽  
Spectral Shifts ◽  
Bivalent Cations ◽  
Polyinosinic Acid ◽  
Polyadenylic Acid ◽  
Polyuridylic Acid ◽  
Calf Thymus

1. The interaction of aflatoxin B1 with different polynucleotides was studied spectrophotometrically. Equations were derived that enable the degree of binding to be determined without first determining the extinction coefficient of the bound form. 2. The interaction with calf thymus DNA obeys first-order relationships with an association constant of 0·40mm−1, but there is some evidence for a secondary binding process from results obtained at 390nm. 3. The spectral shifts decreased in the order polyadenylic acid+polyuridylic acid>DNA>polyadenylic acid>polyadenylic acid+polyinosinic acid. Polycytidylic acid, polyuridylic acid, polyinosinic acid (both single- and triple-stranded), AMP, CMP, GMP and UMP did not interact with aflatoxin. It was concluded that there is a requirement for the amino group of adenine (or possibly guanine) for binding of aflatoxin to polynucleotides to occur. 4. Binding is reversed by increasing ionic strength, and by Mn2+ and Mg2+ in the concentration range studied (0–5mm). The effect of the Mn2+ or Mg2+ was far greater than would be expected on the basis of their ionic strength. With both the bivalent cations and sodium chloride the reversal is greatest with double-stranded polynucleotides. 5. Inhibition in vitro of the DNA-dependent RNA polymerase of Escherichia coli by aflatoxin B1 was detected only in the absence of Mg2+ and at concentrations of Mn2+ below the optimum for RNA synthesis in vitro. 6. The degree of inhibition (maximally 30%) was dependent on the concentration of Mn2+ and decreased during incubation.

Circular dichroism of helical polynucleotide chains

1967 ◽  
Vol 297 (1448) ◽  
pp. 150-162 ◽  
Keyword(s):  
Circular Dichroism ◽  
Nucleic Acids ◽  
Helical Structure ◽  
Optical Rotatory Dispersion ◽  
Random Coil ◽  
Helical Conformation ◽  
Polyadenylic Acid ◽  
V Region ◽  
Circular Dichroïsm ◽  
Circular Dichroic

In contrast to relatively well developed experimental and theoretical studies on polypeptides and proteins (see Gratzer 1967 and McLachlan 1967, this volume) the investigation of optical activity of polynucleotides and nucleic acids were very restricted. The optical rotatory dispersion curves of polynucleotides examined in the visible and near u. v. fit one-term Drude equation regardless of the conformation (Fresco 1961; Levedahl & James 1957; Ts’o, Helmkamp & Sander 1962). Recent circular dichroism (c. d.) measurements of several polynucleotides and nucleic acids (figure 1) indicated clearly the presence of dichroic bands in the u. v. region of base absorption which can be related to the dissymmetrical helical conformation (Brahms 1963). The intensity of circular dichroic bands decreases strongly under the conditions in which the helical structure is unstable and goes to random coil form (Brahms 1964; Brahms & Mommaerts 1964). Thus polyadenylic acid (poly A ) is known according to X-ray data to exist at acid pH in a helical two strand and right handed conformation (Rich, Davies, Crick & Watson 1961). In acid solution the same polyadenylic acid exhibits strong circular dichroic bands which disappear at high temperature (figure 2).

Cinerin C: a macrophyllin-type bicyclo[3.2.1]octane neolignan fromPleurothyrium cinereum(Lauraceae)

2012 ◽  
Vol 68 (8) ◽  
pp. o320-o322
Author(s):  
Ericsson D. Coy-Barrera ◽  
Luis E. Cuca-Suárez ◽  
Michael Sefkow ◽  
Uwe Schilde
Keyword(s):  
Hydrogen Bond ◽  
Circular Dichroism ◽  
Single Crystal ◽  
Absolute Configuration ◽  
Ethanol Extract ◽  
X Ray ◽  
Naturally Occurring ◽  
First Time ◽  
Circular Dichroïsm

The structure of naturally-occurring cinerin C [systematic name: (7S,8R,3′R,4′S,5′R)-Δ8′-4′-hydroxy-5,5′,3′-trimethoxy-3,4-methylenedioxy-2′,3′,4′,5′-tetrahydro-2′-oxo-7.3′,8.5′-neolignan], isolated from the ethanol extract of leaves ofPleurothyrium cinereum(Lauraceae), has previously been established by NMR and HRMS spectroscopy, and its absolute configuration established by circular dichroism measurements. For the first time, its crystal strucure has now been established by single-crystal X-ray analysis, as the monohydrate, C22H26O7·H2O. The bicyclooctane moiety comprises fused cyclopentane and cyclohexenone rings which are almost coplanar. An intermolecular O—H...O hydrogen bond links the 4′-OH and 5′-OCH3groups along thecaxis.

Zum Wirkungsmechanismus von 1-Nitroso-3-nitro-1-methyl-guanidin bei der Mutationsauslösung

1967 ◽  
Vol 22 (5) ◽  
pp. 512-517 ◽  
Author(s):  
P. Chandra ◽  
A. Wacker ◽  
R. Süssmuth ◽  
F. Lingens
Keyword(s):  
Methyl Group ◽  
Polycytidylic Acid ◽  
Polyadenylic Acid ◽  
Polyuridylic Acid ◽  
Acceptor Activity ◽  
Maximum Inhibition

The effect of NNMG on the template activities of different polynucleotides (polyuridylic acid, polycytidylic acid, polyadenylic acid and copolymer of adenylic and guanylic acid 5,5:1) and t-RNS was studied. The maximum inhibition of the messenger activity was found for poly-C, followed by poly-Α and poly-U. The acceptor activity of t-RNA was found to be inhibited by NNMG: maximum for proline, followed by serine, leucine, phenylalanine and lysine. The mechanism of these inhibitions was studied using NNMG radioactively labelled on the methyl group. Different amounts of radioactivity were found in the various polynucleotides and t-RNS.

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