Biology Reference
In-Depth Information
well as in the aging process and age-related neurodegenerative disorders.
However, DNA damage is induced sometimes on purpose, for example, for
immunoglobulin gene diversification.
5,6
The most abundant oxidative genome damage products are oxidation prod-
ucts of purines, namely, 8-oxoguanine (8-oxoG) and formamidopyrimidines
(FapyG and FapyA), while the common oxidized pyrimidines are thymine
glycol and 5-OHU; the latter is generated via oxidative deamination of C.
Except for thymine glycol and the hydantoins, these abnormal bases do not
block DNA replication. The less common oxidized base lesions such as 8-oxoA,
5-formylU, and 5-OHC could also be mutagenic/toxic
7
(
Table I
).
TABLE I
C
OMMON
O
XIDIZED
B
ASES
I
NDUCED BY
R
EACTIVE
O
XYGEN
S
PECIES
(ROS)
Normal DNA bases
4. Thymine
1. Adenine
2. Guanine
3. Cytosine
NH
2
NH
2
O
O
CH
3
N
N
N
N
HN
NH
H
N
H
O
H
2
N
N
N
N
H
O
N
H
Common oxidized base lesions
5-Hydroxycytosine
(5-OHC)
Formamidoadenine
(FapyA)
8-Oxoguanine
Thymine glycol
O
O
H
N
NH
2
CH
3
NH
2
H
HN
NH
HO
N
O
O
N
HO
HO
N
C
H
N
H
H
2
N
N
O
H
O
NH
2
N
H
N
8-Oxoadenine
(8-OxoA)
Formamidoguanine
(FapyG)
5-Hydroxyuracil
(5-OHU)
Dihydrothymine
O
NH
2
O
O
CH
3
H
N
H
N
NH
O
HO
N
N
C
H
HO
H
HN
O
O
N
H
NH
2
N
H
N
H
2
N
O
N
H
Guanidinohydantoin
5-Formyluracil
(5-FormylU)
H
N
O
O
O
HN
O
C
H
N
H
H
2
N
H
O
N
H
Oxidative modifications are shown in
gray.
