| 1. |
- Behravan, G., et al.
(author)
-
THE INTERACTION OF ELLIPTICINE DERIVATIVES WITH NUCLEIC-ACIDS STUDIED BY OPTICAL AND H-1-NMR SPECTROSCOPY - EFFECT OF SIZE OF THE HETEROCYCLIC RING
- 1994
-
In: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 34:5, s. 599-609
-
Journal article (peer-reviewed)abstract
- The DNA interaction of derivatives of ellipticine with heterocyclic ring systems with three, four, or five rings and a dimethylaminoethyl side chain was studied. Optical spectroscopy of drug complexes with calf thymus DNA, poly [(dA-dT).(dA-dT)], or poly [(dG-dC).(dG-dC)] showed a 10 nm bathochromic shift of the light absorption bands of the pentacyclic and tetracyclic compounds upon binding to the nucleic acids, which indicates binding by intercalation. For the tricyclic compound a smaller shift of 1-3 nm was observed upon binding to the nucleic acids. Flow linear dichroism studies show that the geometry of all complexes is consistent with intercalation of the ring system, except for the DNA and poly [(dG-dC).(dG-dC)] complexes of the tricyclic compound, where the average angle between the drug molecular plane and the DNA helix axis was found to be 65 degrees. One-dimensional H-1-nmr spectroscopy was used to study complexes between d(CGCGATCGCG)(2) and the tricyclic and pentacyclic compounds. The results on the pentacyclic compound show nonselective broadening due to intermediate chemical exchange of most oligonucleotide resonances upon drug binding. The imino proton resonances are in slow chemical exchange, and new resonances with upheld shifts approaching 1 ppm appear upon drug binding, which supports intercalative binding of the pentacyclic compound. The results on the tricyclic compound show more rapid binding kinetics and very selective broadening of resonances. The data suggest that the tricyclic compound is in an equilibrium between intercalation and minor groove binding, with a preference to bind close to the AT base pairs with the side chain residing in the minor groove. (C) 1994 John Wiley and Sons, Inc.
|
|
| 2. |
- Doglia, S. M., et al.
(author)
-
QUINACRINE - SPECTROSCOPIC PROPERTIES AND INTERACTIONS WITH POLYNUCLEOTIDES
- 1993
-
In: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 33:9, s. 1431-1442
-
Journal article (peer-reviewed)abstract
- The acridine dye quinacrine and its interactions with calf thymus DNA, poly(dA-dT).poly(dA-dT), and poly(dG-dC).poly(dG-dC) were studied by light absorption, linear dichroism, and fluorescence spectroscopy. The transition moments of quinacrine give rise to absorption bands polarized along the short axis (400-480-nm band), and the long axis (345-nm and 290-nm bands) of the molecule, respectively. Linear dichroism studies show that quinacrine intercalates into calf thymus DNA as well as into the polynucleotides, displaying fairly homogeneous binding to poly (dA-dT).poly(dA-dT), but more than one type of intercalation site for calf thymus DNA and poly(dG-dC).poly(dG-dC). Fluorescence spectroscopy shows that for free quinacrine the pK = 8.1 between the mono- and diprotonated states also remains unchanged in the excited state. Quinacrine bound to calf thymus DNA and polynucleotides exhibits light absorption typical for the intercalated diprotonated form. The fluorescence enhancement of quinacrine bound to poly (dA-dT).poly(dA-dT) may be due to shielding from water interactions involving transient H-bond formation. The fluorescence quenching in poly (dG-dC).poly (dG-dC) may be due to excited state electron transfer from guanine to quinacrine. (C) 1993 John Wiley & Sons, Inc.
|
|
| 3. |
|
|
| 4. |
- Kim, Seog K., et al.
(author)
-
Z- B TRANSITION IN POLY D(G-M5C)2 INDUCED BY INTERACTION WITH 4',6-DIAMIDINO-2-PHENYLINDOLE
- 1993
-
In: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 33:11, s. 1677-1686
-
Journal article (peer-reviewed)abstract
- The Z form of poly [d(G-m5C)2], in presence of Mg2+ ion, is found to be transformed into B form upon interaction with 4',6-diamidino-2-phenylindole (DAPI). The Z --> B transformation is complete at a mixing ratio of about 0.07 DAPI per DNA base pairs, i.e., each DAPI molecule may be related to the conversion of 6-7 base pairs. An interaction between DAPI and poly [d(G-m5C)2] in its Z form at low drug: DNA ratios is suggested from optical dichroism and time-resolved luminescence anisotropy results. The spectroscopic behaviour of DAPI indicates that the Z conformation of DNA does not provide normal binding sites for DAPI, such as groove or intercalation sites, but that the initial association may be of external nature. (C) 1993 John Wiley & Sons, Inc.
|
|
| 5. |
- Lyng, Reidar, 1959, et al.
(author)
-
THE CD OF LIGAND-DNA SYSTEMS .1. POLY(DG-DC) B-DNA
- 1991
-
In: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 31:14, s. 1709-1720
-
Journal article (peer-reviewed)abstract
- A systematic theoretical study of the CD of double-stranded poly (dG-dC) and its complexes with small molecules is presented. The intrinsic CD of the polymer and the induced CD of a transition belonging to a molecule bound to DNA are calculated using the matrix method. The calculations show considerable differences between pyrimidine-purine and purine-pyrimidine binding sites, and we find that the induced CD of a groove bound molecule is one order of magnitude stronger than that of an intercalated molecule. The results form a sound basis for interpreting the CD of ligand-DNA systems in terms of molecular geometry, interactions, and spectroscopy.
|
|
| 6. |
- Lyng, Reidar, 1959, et al.
(author)
-
THE CD OF LIGAND-DNA SYSTEMS .2. POLY(DA-DT) B-DNA
- 1992
-
In: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 32:9, s. 1201-1214
-
Journal article (peer-reviewed)abstract
- A systematic theoretical study of the CD of [poly (dA-dT)]2 and its complexes with achiral small molecules is presented. The CD spectra of [poly (dA-dT)]2 and of poly (dA):poly(dT) are calculated for various DNA structures using the matrix method. The calculated and experimental spectra agree reasonably well for [poly(dA-dT)]2 but less well for poly(dA):poly(dT). The calculated CD spectrum of [poly(dA-dT)]2 fails to reproduce the wavelength region of 205-245 nm of the experimental spectrum. This discrepancy can be explained by a magnetic dipole allowed transition contributing significantly to the CD spectrum in this region. The induced CD of a transition moment of a molecule bound to [poly(dA-dT)]2 is also calculated. As was the case for [poly(dG-dC)]2, the induced CD of a groove bound molecule is one order of magnitude stronger than that of an intercalated molecule. The calculations also show considerable differences between pyrimidine-purine sites and purine-pyrimidine sites. Both signs and magnitudes of the CD induced into ligands bound in the minor groove agree with experimental observations.
|
|
