Lactoperoxidase-catalyzed oxidation of thiocyanate ion: a carbon-13 nuclear magnetic resonance study of the oxidation products

Biochim Biophys Acta. 1992 Oct 20;1159(3):279-85. doi: 10.1016/0167-4838(92)90057-k.


Products formed from the lactoperoxidase (LPO) catalyzed oxidation of thiocyanate ion (SCN-) with hydrogen peroxide (H2O2) have been studied by 13C-NMR at pH 6 and pH 7. Ultimate formation of hypothiocyanite ion (OSCN-) as the major product correlates well with the known optical studies. The oxidation rate of SCN- appears to be greater at pH < or = 6.0. At [H2O2]/[SCN-] ratios of < or = 0.5, OSCN- is not formed immediately, but an unidentified intermediate is produced. At [H2O2]/[SCN-] > 0.5, SCN- appears to be directly oxidized to OSCN-. Once formed, OSCN- slowly degrades over a period of days to carbon dioxide (CO2), bicarbonate ion (HCO3-), and hydrogen cyanide (HCN). An additional, previously unrecognized product also appears after formation of OSCN-. On the basis of carbon-13 chemical shift information this new species is suggested to result from rearrangement of OSCN- to yield the thiooxime isomer, SCNO- or SCNOH.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Catalysis
  • Hydrogen-Ion Concentration
  • Lactoperoxidase / pharmacology*
  • Magnetic Resonance Spectroscopy
  • Oxidation-Reduction
  • Thiocyanates / metabolism*


  • Thiocyanates
  • Lactoperoxidase
  • thiocyanate