The High Reactivity of Peroxiredoxin 2 with H2O2 Is Not Reflected in Its Reaction with Other Oxidants and Thiol Reagents

Abstract

Peroxiredoxin 2 is a member of the mammalian peroxiredoxin family of thiol proteins that is important in antioxidant defense and redox signaling. We have examined its reactivity with various biological oxidants, in order to assess its ability to act as a direct physiological target for these species. Human erythrocyte peroxiredoxin 2 was oxidized stoichiometrically to its disulfide-bonded homodimer by hydrogen peroxide, as monitored electrophoretically under nonreducing conditions. The protein was highly susceptible to oxidation by adventitious peroxide, which could be prevented by treating buffers with low concentrations of catalase. However, this did not protect peroxiredoxin 2 against oxidation by added H 2 O 2 . Experiments measuring inhibition of dimerization indicated that at pH 7.4 catalase and peroxiredoxin 2 react with hydrogen peroxide at comparable rates. A rate constant of 1.3 ؋ 10 7 M ؊1 s ؊1 for the peroxiredoxin reaction was obtained from competition kinetic studies with horseradish peroxidase. This is 100-fold faster than is generally assumed. It is sufficiently high for peroxiredoxin to be a favored cellular target for hydrogen peroxide, even in competition with catalase or glutathione peroxidase. Reactions of t-butyl and cumene hydroperoxides with peroxiredoxin were also fast, but amino acid chloramines reacted much more slowly. This contrasts with other thiol compounds that react many times faster with chloramines than with hydrogen peroxide. The alkylating agent iodoacetamide also reacted extremely slowly with peroxiredoxin 2. These results demonstrate that peroxiredoxin 2 has a tertiary structure that facilitates reaction of the active site thiol with hydrogen peroxide while restricting its reactivity with other thiol reagents.

ACHT4-driven oxidation of APS1 attenuates starch synthesis under low light intensity in Arabidopsis plants

“…3B) is consistent with this hypothesis. The high catalytic efficiency of the 2-Cys Prxs with k cat /K m values of ∼10 7 M −1 ·s −1 and high affinity with K m values in the μM range (20)(21)(22) presumably ensure rapid oxidation kinetics of their Trx partner in response to small changes in low peroxide levels (24,25). In turn, the identified preference of ACHT4 disulfide transfer reaction toward APS1 (Fig.…”

“…Study of the thylakoids-associated ACHT1 revealed that it transmits a disulfide-based oxidative signal in feedback regulation of photosynthesis under homeostasis growth conditions (6). ACHT1 oxidation is driven by 2-Cys Prx, a peroxidase with a low K m for hydrogen peroxide (20)(21)(22) that is conceivably required for the low level of ROS that are typical in signaling events. ACHT1 undergoes rapid redox state changes during the transition of plants from dark to light and afterward, such that, after a short period of net reduction, the ACHT1 pool is maintained in a partially oxidized state in the light.…”

Oxidation of proteins: Basic principles and perspectives for blood proteomics

“…Gaetani et al [152] also demonstrated that catalase is essential for the removal of H 2 O 2 from RBCs, having an activity six times higher than glutathione peroxidase. Peskin et al [153] have recently shown that peroxiredoxin 2 and catalase react with H 2 O 2 at comparable rates. It was hypothesised that catalase and peroxiredoxin play complementary roles in H 2 O 2 detoxification/ signalling due to the different recycling mechanisms used [154]; in RBCs, peroxiredoxin 2 was shown to accumulate as a dimer under H 2 O 2 challenge, which was only slowly converted back to the active monomer by the thioredoxin system.…”

Model for the Exceptional Reactivity of Peroxiredoxins 2 and 3 with Hydrogen Peroxide

“…the secondorder rate constants for the reaction of human Prx2 and Prx3 with H 2 O 2 are ϳ 10 7 M Ϫ1 s Ϫ1 (3,5), compared with ϳ1 M Ϫ1 s…”

“…reactive against peroxynitrite and other peroxides (4,6,7), but less so with other typical thiol-reactive reagents such as chloramines or alkylating electrophiles (5,8). There are six subfamilies (Prx1, Prx6, AhpE (one-cysteine peroxiredoxin from Mycobacterium tuberculosis), Prx5, Tpx, and bacterioferritin comigratory protein), categorized by amino acid sequence, which share a similar catalytic cycle.…”