Received May 22, 2006

Revised Manuscript Received August 17, 2006

Abstract:

In an effort to reconcile conflicting reports regarding the spectra of the human defense factor hypothiocyanite (OSCN^-), we have synthesized OSCN^- by three methods and characterized the product spectroscopically. Method I is lactoperoxidase-catalyzed oxidation of SCN^- by H₂O₂ at pH 7. Method II is hydrolysis of (SCN)₂ at pH 13. Method III is oxidation of SCN^- by OX^- (X = Cl and Br) at pH 13. All three methods produced essentially the same initial UV, ¹³C NMR, and ¹⁵N NMR spectra. The UV spectrum reveals a _max of 376 nm, which is a previously unreported distinguishing feature. The ¹³C NMR spectrum ( = 127.8 ppm at pH 13 vs dioxane at 66.6 ppm) is comparable to those that have been previously reported for OSCN^- as prepared by methods I and II (although in some cases different assignments have been made). However, the ¹⁵N NMR spectrum we measure ( = -80.6 ppm at pH 13 vs NO₃^- at 0 ppm) contrasts with previous reports. We conclude that all three methods produce the same species, and the spectra are now self-consistent with the formulation OSCN^-.

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