Oxygen-mediated spectral oscillations in biomolecules and importance of coexisting tautomers : Case of guanine

Abstract

The result obtained by spectroscopic and quantum chemical studies on the electronic structure, spectra and oxygen-mediated spectral oscillations in guanine have been discussed. The origin of the asymmetric double-well nature of the ground state potential surface of the molecule, suggested by the e experimental results, has been shown theoretically to lie in the simultaneous occurrence of certain tautomers. The spectral oscillations served in this case have been explained in terms of complex ion of guanine with the dissolved Oxygen, electronic excitation and deexcitation of the complex, and accompanying variation in relative populations of the tautomers. Though the specific case of guanine has been discussed, the arguments are also applicable to other systems which occur in more than one tautomeric forms and which complex with oxygen.