Lactoperoxidase catalytically oxidize hydrogen sulfide via intermediate formation of sulfheme derivatives.

The biological chemistry of hydrogen sulfide (HS) with physiologically important heme proteins is in the focus of redox biology research. In this study, we investigated the interactions of lactoperoxidase (LPO) with HS in the presence and absence of molecular dioxygen (O) or hydrogen peroxide (HO). Under anaerobic conditions, native LPO forms no heme-HS complex upon sulfide exposure.

Mechanisms of myeloperoxidase catalyzed oxidation of HS by HO or O to produce potent protein Cys-polysulfide-inducing species.

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.

Hydrogen sulfide activation in hemeproteins: the sulfheme scenario.

Traditionally known as a toxic gas, hydrogen sulfide (H2S) is now recognized as an important biological molecule involved in numerous physiological functions. Like nitric oxide (NO) and carbon monoxide (CO), H2S is produced endogenously in tissues and cells and can modulate biological processes by acting on target proteins. For example, interaction of H2S with the oxygenated form of human hemoglobin and myoglobin produces a sulfheme protein complex that has been implicated in H2S degradation.