Electrochemical Reduction and Oxidation of Eight Unnatural 2'-Deoxynucleosides at a Pyrolytic Graphite Electrode

Abstract

Recently we showed the reduction and oxidation of six natural 2'-deoxynucleosides in the presence of the ambient oxygen using the very broad potential window of a pyrolytic graphite electrode (PGE). Using the same procedure, 2'-deoxynucleoside analogs (dNs) that are parts of an artificially expanded genetic information system (AEGIS) were analyzed. Seven of the eight tested AEGIS dNs provided specific signals (voltammetric redox peaks). These signals, described here for the first time, will be used in future work to analyze DNA built from expanded genetic alphabets, helping to further develop AEGIS technology and its applications. Comparison of the electrochemical behavior of unnatural dNs with the previously documented behaviors of natural dNs also provides insights into the mechanisms of their respective redox processes.

Keywords: electrochemical oxidation; electrochemical reduction; electrochemistry; pyrolytic graphite; unnatural DNA.

Fig. 1.

PGE surface renewal with an adhesive tape (A). Freshly peeled basal plane-oriented PGE surface (B) and sample adsorption from a drop of an analyte (C).

Fig. 2.

Baseline corrected successive LSVs of dX (A), dP (B) and damA (C). Scanning order is indicated by the arrows. In the case of dX LSV scans were performed from 0 V to +1.50, +1.35, +1.15 or +0.50 V, followed by scan from the vertex to −2.00 V (A top) or from 0 V to −2.00, −1.90, −1.80 or −0.70 V, followed by scan from the vertex to +1.7 (A bottom). In the case of dP from 0 V to +1.50, +1.25 or +1.00 V followed by scan from the vertex to −2.00 V (B top) or from 0 V to – 2.00, −1.45 or −1.20 V, followed by scan from the vertex to +1.7 (B bottom). In the case of damA LSVs were performed from 0 V to +1.50, +1.25 or +1.10 V followed by scan from the vertex to −2.00 V (A top) or from 0 V to −1.85, −1.65, −1.50 or −0.50 V, followed by scan from the vertex to +1.7 (A bottom) in case of damA. Insets: structure of the damA (A), dX (B) and dP (C). R=2’-deoxyribosyl moiety.

Fig. 3.

Baseline corrected successive LSVs of disoC. Scanning order is indicated by the arrows. LSVs were performed from 0 V to +1.60, +1.25 or +0.95 V followed by scan from the vertex to −2.00 V (top) or from 0 V to −1.85 or −1.65 V, followed by scan from the vertex to +1.7 (bottom). Inset: structure of the disoC with numbered atoms in aromatic ring. R=2’-deoxyribosyl moiety.

Fig. 4.

Baseline corrected successive LSVs of dV (A), dK (B) and dZ (C). Scanning order is indicated by the arrows. LSVs were performed from 0 V to +1.50, +1.25, +1.08 or +0.95 V followed by scan from the vertex to −2.00 V (A top) or from 0 V to −1.20, −1.00 or −0.65 V, followed by scan from the vertex to +1.7 (A bottom) in case of dV. In case of dK scans were performed from 0 V to +1.50, +1.40 or +1.10 V followed by scan from the vertex to −2.00 V (B top) or from 0 V to −1.50, −1.40 or −1.10 V, followed by scan from the vertex to +1.7 (B bottom) and in case of dZ from 0 V to +1.50, +1.20, +0.90 V followed by scan from the vertex to −2.00 V (C top) or from 0 V to – 1.45, −1.00 or −0.70 V, followed by scan from the vertex to +1.7 (C bottom). Insets: structure of the damA (A), dX (B) and dP (C). R=2’-deoxyribosyl moiety.

Fig. 5.

Recordings of two successive CVs after single adsorption of indicated 1 mM nucleoside: −0.3 to −1.1 V and back to −0.3 V, followed by 5 CV cycles between −0.3 and +0.4 V – starting at −0.3 V. Measurements performed in deaerated electrolyte (top) or in the presence of the ambient oxygen (bottom).