An experimental and theoretical core-level study of tautomerism in guanine.
The core level photoemission and near edge X-ray photoabsorption spectra of guanine in the gas phase have been measured and the results interpreted with the aid of high level ab initio calculations. Tautomers are clearly identified spectroscopically, and their relative free energies and Boltzmann populations at the temperature of the experiment (600 K) have been calculated and compared with the experimental results and with previous calculations. We obtain good agreement between experiment and the Boltzmann weighted theoretical photoemission spectra, which allows a quantitative determination of the ratio of oxo to hydroxy tautomer populations. For the photoabsorption spectra, good agreement is found for the C 1s and O 1s spectra but only fair agreement for the N 1s edge.
Plekan
Oksana
O
Sincrotrone Trieste, in Area Science Park, I-34012 Basovizza (Trieste), Italy.
Feyer
Vitaliy
V
Richter
Robert
R
Coreno
Marcello
M
Vall-Llosera
Gemma
G
Prince
Kevin C
KC
Trofimov
Alexander B
AB
Zaytseva
Irina L
IL
Moskovskaya
Tatyana E
TE
Gromov
Evgeniy V
EV
Schirmer
Jochen
J
D000042:Absorption; D002244:Carbon / Q000737:chemistry; D006147:Guanine / Q000737:chemistry*; D007536:Isomerism; D008958:Models, Molecular; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry; D009696:Nucleic Acids / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D011789:Quantum Theory; D013057:Spectrum Analysis; D013696:Temperature
D009696:Nucleic Acids; D006147:Guanine; D002244:Carbon; D009584:Nitrogen; D010100:Oxygen