Aqueous Chemistry of Sulfenyl Thiocyanates: The familiar roles of thiols in cellular oxidant defense systems are altered when reactive conjugates are formed.  These so-called reactive sulfur species (RSS) can exhibit beneficial or deleterious biochemistry.  While most RSS that have been studied to date are organic compounds, it has been suggested that the inorganic RSS hypothiocyanite (OSCN^-), an antimicrobial agent that is produced by myeloperoxidase, eosinophil peroxidase, lactoperoxidase, and salivary peroxidase, may target key protein sulfhydryl groups in pathogens, perhaps vis-à-vis sulfenyl thiocyanates (RSSCN).  Sulfenyl thiocyanates are relatively esoteric compounds due to their general instability. Nonetheless, despite the aforementioned implication of RSSCN intermediates in the non-immune defense system, and similar proposed intermediates in the synthesis of polypeptides, prior to our studies there exist no bona-fide examples of such compounds in aqueous solution.  We have recently demonstrated that the equilibrium mixture OSCN^-=HOSCN=(SCN)₂=(SCN)₃^- reacts with cysteine derivatives to yield sulfenyl thiocyanates.  The products of Scheme 1 represent the first organic species to be characterized that are derived from hypothiocyanite in water and the first water-soluble sulfenyl thiocyanates.  This work has been published (Ashby, M. T.; Aneetha, H., J. Amer. Chem. Soc.  2004, 126, 10216-10217).   

Acknowledgement:  We are very grateful to the Petroleum Research Fund (PRF#42850-AC4), the Oklahoma Center for the Advancement of Science and Technology (HR02-019), and the Department of Education (GAANN) for their financial support of this project.