| Attributs | Valeurs |
|---|
| type
| |
| Is Part Of
| |
| Subject
| |
| Title
| - Local Conformational Changes Induced in B-DNA by Ethidium Intercalation
|
| has manifestation of work
| |
| related by
| |
| Author
| |
| Abstract
| - Structural effects of binding the intercalating drug ethidium bromide (EtBr) to 160 base pair(bp) fragments of nucleosomal calf thymus DNA have been probed by the method of Raman differencespectroscopy. With the use of a near-infrared (NIR) laser source to excite the Raman spectrum at 752 nm,vibrational signatures of both the EtBr intercalant and DNA target have been identified in spectra of thedrug−DNA complexes. Analysis of the results obtained on complexes consisting of 1 EtBr bound/10 bpleads to the following conclusions: (i) Raman markers diagnostic of DNA phosphodiester conformationare converted from the B type to the A type with EtBr binding, commensurate with the proportion ofethidium-bound nucleotides in the complex. (ii) Ethidium binding converts deoxynucleoside sugar puckersfrom the C2‘-endo to the C3‘-endo conformation, also consistent with binding stoichiometry. Bothpyrimidine and purine deoxynucleoside sugar puckers are perturbed by the phenanthridinium ringintercalation. (iii) Phenanthridinium insertion between bases is accomplished with no apparent change inhypochromicities of purine or pyrimidine Raman markers, indicating that base−phenanthridiniuminteractions provide compensatory hypochromic effects. (iv) Novel Raman markers of helix unwindinghave been identified and assigned primarily to methylene deformation modes of the deoxyribosyl C2‘H2and C5‘H2 groups. The present study provides new insights into drug−DNA recognition in solution anddemonstrates the feasibility of NIR−Raman spectroscopy for structural studies of highly chromophoricDNA complexes.
|
| article type
| |
| is part of this journal
| |
