Mechanisms of myeloperoxidase catalyzed oxidation of H2S by H2O2 or O2 to produce potent protein Cys-polysulfide-inducing species.

Mechanisms of myeloperoxidase catalyzed oxidation of H2S by H2O2 or O2 to produce potent protein Cys-polysulfide-inducing species.
Free Radic Biol Med. 2017 Oct 30;:
Authors: Garai D, Ríos-González BB, Furtmüller PG, Fukuto JM, Xian M, López-Garriga J, Obinger CC, Nagy P
Abstract
The interaction of heme proteins with hydrogen sulfide is gaining attention as an important element in sulfide-mediated protection against oxidative stress and in regulation of redox signaling. In our previous study we reported the efficient reversible inhibition of myeloperoxidase (MPO) activity by sulfide and the kinetics of the reactions of sulfide with ferric MPO, Compound I and Compound II. Here we provide several lines of evidence that a central intermediate species in the turnover of MPO by sulfide is the Compound III state. Compound III is formed in the reactions of sulfide with ferric or ferrous MPO in the presence of oxygen or via the reductions of Compound I or Compound II by sulfide. The regeneration of active ferric MPO from Compound III is slow - representing the rate-limiting step during turnover - but facilitated by ascorbate or superoxide dismutase. These catalytic cycles produce inorganic sulfane sulfur species, which were shown to promote protein Cys persulfidation. Based on compiling experimental data we propose that in contrast to hemoglobin, myoglobin, catalase or lactoperoxidase the formation of a sulfheme derivative in the oxidati...

Source: Free Radical Biology and Medicine - October 30, 2017 Category: Biology Authors: Garai D, Ríos-González BB, Furtmüller PG, Fukuto JM, Xian M, López-Garriga J, Obinger CC, Nagy P Tags: Free Radic Biol Med Source Type: research