Selenium Atom-Specific Mutagenesis (SAM) for Crystallography, DNA Nanostructure Design, and Other Applications - DNA Nanotechnology: From Structure to Function - page 48

3.5 Tellurium-Modified Nucleic Acids

Tellurium, as another chalcogen element with much larger atomic radius and higher
metallicity, is also of great interest in providing new functions and properties into
DNA. Huang lab pioneered the research of the Te-modified DNA for structure-
and-function studies. The first tellurium-derivatized oligonucleotides were made by
synthetic approach in 2009 [ 21 ]. In this chapter, synthesis of the 2 0 -TeMe- and 2 0 -
TePh-containing oligonucleotides was reported. Interestingly, the Te-DNA showed
distinct redox, elimination, as well as self-cleavage properties (Scheme 3.10 ), when
treated under different conditions [ 21 , 23 ].
Tellurium modification was introduced to the 5-position of thymidine as well
[ 22 ]. Thermal denaturing and crystallographic studies revealed that the 5-TePh-
DNA has the similar duplex stability and overall structure as the native DNA.
More interestingly, the Te-DNA is conductive (Fig. 3.9 ) under scanning tunneling
microscope (STM), indicated by the molecular image and shape, while the

a

Intensity (%)
100

2599.3446

Full length
8mer

90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0

b

1856.2911

Fragmented
6mer

Full length
8mer

2599.3445

1300.2094

999 1602 2206 2808 3411

Mass (m/z)

Scheme 3.10 Redox, elimination, and self-cleavage properties of the Te-DNAs

Fig. 3.9 The STM images of the Te-modified DNA duplex and corresponding native duplex on
HOPG. The arrows indicate the edges or current peaks of the measured molecules. ( a ) Topographic
image of Te-duplex; ( b ) current image of Te-duplex; ( c ) topographic image of native duplex; ( d )
current image of native duplex. The sample bias is 0.50 V; the current set point is 100 pA