Polysulfides in Biology: From Intricate Chemistry to an Astonishing Yet Hidden Biological Activity

The last decade has witnessed a growing interest in natural and synthetic polysulfanes and their potential uses in Medicine and Agriculture. Whilst the chemistry and biochemistry of these organic sulfur compounds is slowly emerging and biological applications are being put into practice, their inorganic equivalents, the hydrogen polysulfides, have attracted little attention so far. Recently, studies conducted in the field of hydrogen sulfide (H2S) signaling have revealed a potential role of such simple sulfur molecules in the redox control of cysteine proteins and associated, extensive cellular signaling. It is therefore worthwhile to consider more closely the chemistry of inorganic polysulfides, their possible formation and occurrence in Biology and likely interactions with biologically relevant functional groups and molecules. Here, a specific focus seems to be on thiol and disulfide groups in proteins and enzymes of the cellular thiolstat.