Chemistry Reference
In-Depth Information
Table 11.2.
Radiolysis of N
2
O- and N
2
O/O
2
-saturated solutions of polynucleotides, poly-
deoxyribonucleotides and ssDNA.
G
values of counter-ion release and strand breakage
(unit: 10
−7
mol J
−1
). (Lemaire et al. 1984; Adinarayana et al. 1988)
Substrate
G (counter-ion release)
G (strand breakage)
N
2
O-saturated
Poly(U)
20
2.4
Poly(A)
4.4
0.44
Poly(C)
18
2.2
Poly(G)
0.4
<0.2
Poly(dA)
20
2.3
Poly(dC)
12.3
1.4
Poly(dT)
5.0
0.57
Poly(dU)
4.1
0.46
Poly(dG)
0.75
0.09
ssDNA
7.3
0.83
N
2
O/O
2
-saturated
Poly(U)
23
2.6
Poly(A)
8.5
1.04
Poly(C)
10.5
1.25
Poly(G)
≈
0
<0.2
ssDNA
4.6
0.62
The
•
NO
2
radical does not react with any of the nucleobases, but when G
•
is
formed by one-electron oxidation, e.g., by CO
3
•
−
, in the presence of
•
NO
2
, recom-
bination occurs thereby forming 8-nitroguanine (Joffe et al. 2003a).
11.2.2
Poly(U)
Poly(U) is predominantly attacked by
•
OH at the base moiety (93%; 70% add to
the
C
(5) position and 23% to the
C
(6) position) and only a small fraction of
•
OH
(7%) abstracts an H atom from the sugar moiety [reactions (1)-(3)] (Deeble et al.
1986).
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