Rapid freeze-quench ENDOR study of chloroperoxidase compound I: the site of the radical. Academic Article uri icon


  • The classical heme-monooxygenase active intermediate, compound I (Cpd-I), incorporates a heme which is oxidized by two equivalents above the resting ferric state, one equivalent associated with a ferryl center, [Fe=O]2+ (FeS = 1), and the other with an active-site radical (RS = 1/2). Theoretical calculations on models of a Cpd-I with a thiolato axial ligand have presented divergent views about its electronic structure. In one picture, the radical is on the porphyrin; in the other, it is on the sulfur. In this report, ENDOR spectroscopy answers the question, does Cpd-I of the enzyme chloroperoxidase contain a porphyrin pi-cation radical or an iron-bound cysteinyl radical: the radical is predominantly on the porphyrin, with spin density on sulfur having an upper bound, rhoS

published proceedings

  • J Am Chem Soc

altmetric score

  • 8.08

author list (cited authors)

  • Kim, S. H., Perera, R., Hager, L. P., Dawson, J. H., & Hoffman, B. M

citation count

  • 69

complete list of authors

  • Kim, Sun Hee||Perera, Roshan||Hager, Lowell P||Dawson, John H||Hoffman, Brian M

publication date

  • May 2006