Dynamic redox cycling of hydrogen sulfide and polysulfide species could represent an important regulatory element in sulfur biology

Abstract

The biochemical actions of Reactive Sulfur Species (RSS) are in the focus of redox signaling studies. Following the rapidly rising attention to the biological actions of H2S, in recent years an increasing number of investigations emphasize the significance of polysulfide species in sulfur biology. It is now widely accepted that polysulfides are highly abundant in biological systems with fundamental physiological and pathophysiological roles. The understanding of polysulfide producing enzymatic and non-enzymatic pathways is rapidly evolving. In addition, we demonstrated that the thioredoxin and glutathione systems can efficiently reduce inorganic and Cys-polysulfides via a number of different pathways. Beside the enzymatic interconversion of RSS, delicate speciation equilibria exist between the different forms of these species. Our mechanistic studies emphasize the fact that sulfide and polysulfides are indeed dynamically redox cycling species, which we propose should be an important regulatory element in sulfur biology.