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NO
3
+ CO
2
67%
ONOO + CO
2
33%
NO
2
+ CO
3
TyrO
k
14
= 4.5 × 10
7
/M/s
TyrOH + CO
3
TyrO
Dityrosine
2k
15
= 4.5 × 10
8
/M/s
HCO
3
k
17
= 3 × 10
9
/M/s
k
16
= 3.2 × 10
5
/M/s
NO
2
0.45 3-NO
2
-TyrOH + Products
NO
2
NO
2
+ H
Figure 5.15.
Mechanism of nitration and oxidation of tyrosine by peroynitrite in the
presence of CO
2
at pH 7.5 (adapted from goldstein and Merényi [132] with the permis-
sion of Elsevier Inc.).
+ ONOO
-
+ CO
2
OH
OH
OH
+
[ONO-OCO
2
-
]
1
+
+ NO
2
+ HCO
3
-
19.1
NO
2
+ CO
3
-
‡
11.9
‡
5.2
O
•
8.0
H
0.8
0.0
NO
2
-CO
3
-
+
NO
2
O
H
-6.2
‡
O
H
+ ONOOCO
2
-
OH
-17.2
OH
-22.4
+ HCO
3
-
H + HCO
3
-
NO
2
ONO
2
OH
NO
2
OH
-49.9
Reaction coordinate
Figure 5.16.
The mechanisms of tyrosine nitration by peroxynitrous acid investigated
with the CBS-QB3 method (adapted from gunaydin and Houk [288] with the permis-
sion of the American Chemical Society). See color insert.
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