Measurement of Protein Persulfidation: Improved Tag-Switch Method.

Hydrogen sulfide (HS) is an endogenously produced signaling gasotransmitter, generated by the enzymes cystathionine γ-lyase, cystathionine β-synthase, and 3-mercaptopyruvate sulfurtransferase. The involvement of HS in numerous physiological, as well as pathophysiological conditions, was established over the past decade. However, the exact mechanism(s) of regulation of the biological functions by HS are under active investigations. It is proposed that the oxidative posttranslational modification of protein cysteine residues, known as persulfidation, could be the main mechanism of action of HS. Protein persulfides show similar reactivity to thiols, which represents one of the main obstacles in the development of a reliable method for detection of this specific protein modification. Subsequently, having a selective method for persulfide detection is of utmost importance in order to fully understand the physiological and pathophysiological role of HS. Several methods have been proposed for the detection of protein persulfidation, all of which are highlighted in this chapter. Furthermore, we provide a detailed description and protocol for the first selective persulfide labeling method, a tag-switch method, developed in our group.