We theoretical studied the charge transfer efficiency for donor-acceptor pairs in DNA duplexes containing damaged nucleosides. The donor was 2-aminopurine (Ap) while the acceptor was guanine (G), 8-oxoguanine (OxoG) or 2,6-diamino-4-oxo-5-formamidopyrimidine (FapyG). The OxoG and FapyG are mutations of normal guanine that occur owing to interaction of DNA with free radicals. The human 8-oxoguanine DNA glycosylase 1 (hOGG1) repair enzyme that performs excision of damaged bases, however, the exact excision mechanism is currently unknown. Recently, we proposed new catalytic scheme for hOGG1 enzyme.[1,2] In the current study we wanted to find out whether the base excision by hOGG1 could be in principle monitored in real time employing fluorescence spectroscopy. In our previous studies on charge transfer the calculated donor – acceptor coupling integrals described successfully modulation of charge transfer efficiency that was measured in DNA molecules.[2,3] In particular, the coupling integrals described quenching of fluorescence radiation from 2-aminopurine by guanine in relation with the hole transfer from Ap to G.[3,4] The calculated coupling integrals indicated that guanine is better quencher than OxoG or FapyG. The results indicated that experimental detection of damaged nucleosides within DNA duplex employing fluorescence spectroscopy is possible.
This work was supported by the Grant Agency of the Czech Republic 18-14990S. The access to the MetaCentrum computing facilities is appreciated.