Table 4.

Second order rate constants for the oxidation of selected protein thiols in comparison to cysteine.

R-SH + H2O2	Rate constant (M−1 s−1)	Conditions	References
Cysteine (pKa 8.3)	20	37 °C, pH 7.4	[77]
H. sapiens Prx 2 (2-Cys Prx) (pKa 5.3)	1 × 108	25 °C, pH 7.4	[191]
X. fastidiosa Prx Q	4.5 × 107	25 °C, pH 7.4	[192]
S. typhimurium AhpC (2-Cys Prx)	4 × 107	25 °C, pH 7.0	[193]
T. cruzi TXNPx	3 × 107	25 °C, pH 7.4	[97]
S. cerevisiae Tsa 1 (2-Cys Prx)	2.2 × 107	25 °C, pH 7.4	[99]
S. cerevisiae Tsa 2 (2-Cys Prx)	1.3 × 107	25 °C, pH 7.4	[99]
H. sapiens Prx 5 (2-Cys Prx) (pKa 5.1)	3 × 105	25 °C, pH 7.4	[194]
Glutathione peroxidases (GPxs)	105–108	pH 6.7–7.6	[50]
M. tuberculosis AhpE (1-Cys Prx) (pKa 5.2)	8.2 × 104	25 °C, pH 7.4	[26]
OxyR	2.3 × 105	37 °C, pH 7.4	[9,61]
NADH peroxidase (H10Q mutant)	1.94 × 104	5 °C, pH 7.0	[195]
GAPDH (pKa 8.3)	2.8 × 103	25 °C, pH 7.4	[70]
Yeast GR EHR (Cys63) (pKa 3.7)	0.005	5 °C, pH 7.0	[178]
Cdc25A	69	20 °C, pH 7.0	[180]
Cdc25B (pKa 5.8)	164	20 °C, pH 7.0	[180]
	332	37 °C, pH 7.4	[180]
Cdc25C	120	20 °C, pH 7.0	[180]
Papain (Cys protease) (pKa 3.4)	62	23 °C, pH 7.0	[196]
PTP1B (PTPs) (pKa 5.5)	9	30 °C, pH 7.0	[57]
	42.8	25 °C, pH 7.0	[197]
LAR (PTPs)	14	30 °C, pH 7.0	[57]
VHR (PTPs)	18	30 °C, pH 7.0	[57]
SHP-1	2.0	25 °C, pH 7.5	[198]
SHP-2	2.4	25 °C, pH 7.5	[198]
ΔSHP-1	9.4	25 °C, pH 7.5	[198]
ΔSHP-2	8.8	25 °C, pH 7.5	[198]
MKP3	9.6	20 °C, pH 8.0	[199]
LMV-PTP (isoform 1)	13.1	25 °C, pH 7.5	[200]
Human serum albumin (pKa 8.3–8.6)	2.7	37 °C, pH 7.4	[177]