2-Aminopurine optical spectra: Solvent,pentose ring,and DNA helix melting dependence |
| |
Authors: | Kervin Evans Daguang Xu Younsik Kim Thomas M Nordlund |
| |
Institution: | (1) Department of Physics, University of Alubama at Birmingham, UAB Station, 35294 Birmingham, Alabama |
| |
Abstract: | 2-Aminopurine (2AP) absorption and fluorescence excitation and emission spectra in a series of solvents have been measured to assess effects of solvent polarity. Emission spectra of the free base shift to the red in solvents of a higher dielectric constant, including water but excepting dioxane. Excitation spectra also red-shift, except in water. A change in dipole moment of 2.8 D upon excitation is obtained from a Bilot-Kawski plot which includes data from potentially anomolous solvents such as alcohols but which excludes dioxane and aqueous solvents. Attachment of ribose or 2 -deoxyribose causes 1 to 2-nm shifts in the position of fluorescence excitation and emission spectra of 2AP in water and little change in fluorescence yield. Melting of the DNA duplex dCTGA(2AP)TTCAG]2 yields a blue shift of the excitation and no shift of the emission spectrum-results consistent with increased exposure to water and formation of 2AP-water H bonds in the ground state. The spectral shift occurs 5°C or more below the helix melting temperature, implying a premelting structural change in the decamer. |
| |
Keywords: | 2-Aminopurine nucleosides fluorescence absorption spectroscopy solvent effect DNA melting |
本文献已被 SpringerLink 等数据库收录! |
|