Angew. Chem. Int. Ed. http://doi.org/f27zcg (2015)
The researchers built on previous work that had identified the formation, within a duplex, of a linkage between the abasic site (Ap) of one oligonucleotide — generated by the loss or removal of a coding nucleobase — and a guanine or adenine residue of the opposite strand. Now, Gamboa Varela and Gates have instead crosslinked the Ap residue with a non-natural nucleobase, N4-amino-2′-deoxycytidine (dC*), installed for this purpose at a defined location. The Ap and dC* residues react through their respective aldehyde and hydrazine moieties to form a covalent hydrazone linkage. The complementary strands containing Ap and dC* were prepared through straightforward treatments of the corresponding deoxyuridine- and cytosine-containing oligonucleotides, using the enzyme uracil DNA glycosylase, and bisulfite and hydrazine in sodium phosphate, respectively. The Ap and dC* moieties are positioned in a manner that facilitates the formation of the hydrazone crosslink: the two residues are offset by one base in the hybridized duplex, and dC* is mispaired.
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