Spontaneous self-association of adenine and uracil in polycrystals from low temperature FTIR spectra in the range below 1000 cm(-1).
FTIR spectra of solid samples of co-crystallized adenine and uracil were measured at 10K in the range below 1000cm(-1). New bands ascribable to the N3H (uracil) and NH(2) (adenine) out of plane vibrations, which disappear upon D-exchange, were revealed in comparison with the spectra of pure polycrystalline adenine and uracil obtained in the same conditions. The observed changes relate to the same groups that establish the H-bonds in base pairs of naturally occurring nucleic acids, despite the presence of an extra proton donor NH-group in both molecules. The well-established empirical correlation between the out of plane NH vibrational frequencies and H-bond energies was successfully applied for estimation of the latter in the mixed crystal.
Rozenberg
M
M
Department of Inorganic and Analytical Chemistry, The Hebrew University of Jerusalem, Givat Ram, 91904 Jerusalem, Israel. markroz@chem.ch.huji.ac.il
Shoham
G
G
Reva
I
I
Fausto
R
R
D000225:Adenine / Q000032:analysis / Q000737:chemistry*; D003461:Crystallography; D008958:Models, Molecular; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D014498:Uracil / Q000032:analysis / Q000737:chemistry*; D014961:X-Ray Diffraction
D014498:Uracil; D000225:Adenine