2.1 Preparation of AFB1-FapyGua-containing
oligodeoxynucleotides
The 11-mer oligodeoxynucleotides site-specifically modified with
AFB1-FapyGua were prepared from unmodified
oligodeoxynucleotides containing the unique N7-guanine alkylation site
(5′-CCATAGC TACC-3′, 5′-CCATCGC TACC-3′,
5′-CCATTGC TACC-3′, or 5′-CCATCGA TACC-3′, where the target
and neighboring sites are underlined). These were annealed with the
corresponding 6-mer oligodeoxynucleotides (5’-TAGCTA-3’, 5’-TAGCGA-3’,
5’-TAGCAA-3’, and 5’-TATCGA-3’) to form partially double-stranded DNA
structures and reacted with AFB1 exo -8,9-epoxide.
The conditions for chemical modifications, purification by reverse-phase
HPLC, and characterization by mass spectrometry were previously
described (Li et al. 2015; Tomar et al. 2021).