Metabolic Turnover of Hydrogen Sulfide

which oxidizes H 2 S to persulfide. SQRs were initially identified in invertebrates, and their mammalian counterpart SQRs were later discovered (Theissen et al., 2003; Theissen and Martin, 2008). In the presence of O 2 and water, sulfur dioxygenase oxidizes persulfide to sulfite, which is combined with another persulfide molecule by sulfur transferase rhodanese in order to producing thiosulfate (Figure 1). Because H 2 S consumption by a dioxygenase is high in the presence of O 2 (Furne et al., 2008), high H 2 S production is offset by rapid H 2 S clearance under aerobic conditions, accounting for very low basal levels of H 2 S. Small deviations in the rates of H 2 S production and clearance may lead to rapid and several-fold changes in the H 2 S levels (Vitvitsky et al., 2012).