Biomedical Engineering Reference
In-Depth Information
Fig. 3.3
2
0
-SeMe-T-containing DNA structure. (
a
) Superimposed structure 2
0
-SeMe-T DNA
(5
0
-GT
2
0
-Se
GTACAC-3
0
)
2
(PDB ID: 2HC7; resolution: 1.4 A; in
cyan
) with native DNA
(5
0
-GTGTACAC-3
0
)
2
, (PDB ID: 1DNS; resolution: 2.0 A; in
green
); only single strand is presented
here. (
b
) Structure and electron density map of 2
0
-SeMe-T in duplex
displaced it by a selenium functionality [
20
,
31
]. Trifluoromethanesulfonyl chloride
(T
f
-Cl) was chosen as the activating reagent due to its high reactivity and good
leaving ability. Moreover, an interesting redox property of 2
0
-Se-G (Scheme
3.4
)
was also observed [
20
]. Synthesis and crystal structures of 2
0
-Se-purine analogs
were also reported by Huang's lab as well [
33
,
34
]. By the combination of chemical
synthesis and enzymatic ligation, RNAs containing multiple 2
0
-Se groups were also
prepared for crystallographic study [
31
].
Summary of 2
0
-Se-Derivatized Nucleic Acid
3.2.2.3
Now, all of the building blocks for the 2
0
-SeMe DNA and RNA synthesis are avail-
able for customized derivatization of DNAs and RNAs. These Se-phosphoramidites
can be conveniently prepared and incorporated into oligonucleotides with high
yield; the purification of modified oligonucleotides is also straightforward. There
are several reasons that the 2
0
-Se derivatization has greater potential than the broadly
used 5-Br derivatization for phasing.
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