Consecutive Silver(I) Ion Incorporation into Oligonucleotides containing Cytosine‐Cytosine Mispairs

Abstract

Herein, the consecutive incorporation of Ag I ion into the dsDNA containing adjacent CÀ C mispairs is demonstrated. The melting temperature (T m) was 8°C higher for DNA containing three CÀ C mispairs upon the addition of three Ag I ions as compared to the Ag I-free DNA, and no T m was obtained in the presence of excess Ag I ion, indicating a stable bridging of C-Ag I À C upon the incorporation of the stoichiometric amount of Ag I per CÀ C mispair. The circular dichroism (CD) spectra of the dsDNA showed a negative peak at~270 nm in the presence of excess Ag I , implying that significant structural changes and a potential aggregation of DNA occurred. Subsequently, the Ag I-mediated DNA strands are immobilized on Au surfaces. Their electrochemical properties are monitored using CV, EIS and SECM showing increased overpotentials and charge-transfer resistances, and decreased the rate constant in the presence of an excess of Ag I , respectively. These results are further supported by the XPS and sulfide-Au reductive desorption measurements.

6-Pyrazolylpurine and its deaza derivatives as nucleobases for silver(I)-mediated base pairing with pyrimidines

“…4 d), accompanied by a slight red-shift of the Cotton effect. Such a change in the CD spectrum had been reported before for duplexes containing non-Watson–Crick-type Ag(I)-mediated base pairs involving canonical nucleobases [ 15 , 56 , 57 ]. It may therefore be considered further indication for the non-specific binding of the excess silver(I) to the duplexes under investigation.…”

“…Starting from a typical B-DNA-type CD spectrum, the decrease in intensity of the positive Cotton effect at ca. 280 nm accompanied by its red-shift is strongly suggesting the beginning of a structural rearrangement towards duplexes containing non-Watson–Crick-type Ag(I)-mediated base pairs involving canonical nucleobases [ 15 , 56 , 57 ]. Hence, an initial non-specific binding of Ag(I) can be concluded for duplexes III X bearing a central X:T pair.…”

A Novel AgI‐DNA Rod Comprising a One‐Dimensional Array of 11 Silver Ions within a Double Helical Structure

“…By contrast, the shapes of the transition curves for ODN‐I were blurred (Figure 3c, g). Similar decreases of ellipticity around 275 nm have been observed in Ag I titration experiments with C 6 [11a] and duplexes containing C–C pairs [11b] …”

Silver(I)‐mediated hetero base pairs of 6‐pyrazolylpurine and its deaza derivatives

“…When a metal‐mediated base pair is formed, its formation is typically accompanied by an increase in the duplex melting temperature T m until all designated metal‐binding sites are saturated [17] . Excess metal ions then lead to an additional minor increase only, which is often attributed to non‐specific binding to the canonical nucleobases [12c,18] . Hence, in this study melting curves were recorded for the antiparallel‐stranded duplexes in the presence of 0, 1, 2, 3, and 6 μ m Ag I (for 1 μ m duplex concentration).…”