Chemistry Reference
In-Depth Information
TABLE 5.6. Second-Order Rate Constants of Peroxynitrite Reactions with Free
Amino Acids, Peptides, and Nonmetal Containing Proteins [248]
pH
a
Amino Acid, Peptide, or Protein
t
(°C)
k
(/M/s)
Reference
glutathione peroxidase
(selenocysteine, reduced)
b
7.4
25
8 × 10
6
[262]
glutathione peroxidase
(selenocysteine, oxidized)
7.4
25
7.4 × 10
5
[262]
Peroxiredoxin alkylhydroperoxide
reductase(cysteine)
7.0
NR
1.51 × 10
6
[263]
Protein tyrosine phosphatases
(cysteine)
7.4
37
2-20 × 10
7
[264]
Creatine quinase (cysteine)
6.9
NR
8.85 × 10
5
[265]
glyceraldehyde 3-phosphate
dehydrogenase(cysteine)
7.4
25
2.5 × 10
5
[266]
Human serum albumin (whole
protein)
7.4
37
9.7 × 10
3
[261]
Human serum albumin (cysteine)
7.4
37
3.8 × 10
3
[261]
Cysteine
7.4
37
4.5 × 10
3
[205]
glutathione
7.4
37
1.36 × 10
3
[267, 268]
7.0 × 10
2
Homocysteine
7.4
37
[267]
N-Acetylcysteine
7.4
37
4.15 × 10
2
[267]
Cysteine sulfinic acid
7.4
25
7.6 × 10
1
[216]
Hypotaurine
7.4
25
7.7 × 10
1
[216]
Lipoic acid (disulfide)
7.4
37
1.4 × 10
3
[267]
Selenomethionine
7.8
25
1.48 × 10
3
[210]
Methionine
7.4
25
1.7-1.8 × 10
2
[206, 269]
3.64 × 10
2
7.4
37
[261]
1.6 × 10
3
N-Acetylmethionine
6.3
25
[269]
Threonylmethionine
7.4
27
2.83 × 10
2
[273]
glycylmethionine
7.4
27
2.80 × 10
2
[273]
Lysozyme
7.4
37
7.0 × 10
2
[248]
Tryptophan
7.4
37
3.7 × 10
1
[274]
a
pH: This column shows the pH at which the rate constant was determined.
b
In the case of proteins, the critical residue is shown in parentheses.
NR, not reported.
rate constants as a function of pH for thiols were a bell-shaped curve. This
indicates the protonated form of one species reacted with the anionic species
of the other. However, the rate constants for a number of thiols increased as
the p
K
a
of the thiol compound decreased, suggesting ONOOH was the reac-
tive species with the anionic thiolate (RS
−
) [267].
The reactions of peroxynitrite with RS
−
form corresponding disulfides and
nitrites (Table 5.7). disulfide is formed through an intermediate of sulfenic
acid, RSOH (Eq. 5.43), which reacts further with another molecule of thiol to
form the corresponding disulfide (Eq. 5.44) [270]:
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