Oxygen-17 nuclear magnetic resonance spectroscopic studies of carbonmonoxyperoxidases

H. C. Lee, K. Cummings, K. Hall, L. P. Hager, E. Oldfield

Research output: Contribution to journalArticlepeer-review


We have obtained oxygen-17 (17O) nuclear magnetic resonance (NMR) spectra of C17O ligands bound to ferrous horseradish peroxidase isozyme A, isozyme C, and ferrous chloroperoxidase, as a function of pH. Our results show that the peroxidases exist in two distinct states, the acidic and alkaline forms, which undergo reversible acid-base-induced transitions characterized by a single pK value. The two forms are characterized spectroscopically in much the same way in all three proteins, suggesting a similar structural origin for the transition process. In particular, the 17O NMR signal of the acidic form is approximately 7 ppm more shielded than that of the alkaline form, and the CO ligand in the acidic form appears to have a smaller 17O nuclear quadrupole coupling constant than that of the alkaline form. We have also obtained the pK values and exchange rates for all three peroxidases. The results indicate that a similar structural change may be involved in the transition process in all three peroxidases.

Original languageEnglish (US)
Pages (from-to)16118-16124
Number of pages7
JournalJournal of Biological Chemistry
Issue number31
StatePublished - 1988

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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