Calcium-dependent conformation of a heme and fingerprint peptide of the diheme cytochrome c peroxidase from Paracoccus pantotrophus

Sofia Rocha Pauleta, Yi Lu, Celia F. Goodhew, Isabel Maria Andrade Martins Galhardas de Moura, Graham W. Pettigrew, John Allen Shelnutt

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11 Citations (Scopus)

Abstract

The structural changes in the heme macrocycle and substituents caused by binding of Ca2+ to the diheme cytochrome c peroxidase from Paracoccus pantotrophus were clarified by resonance Raman spectroscopy of the inactive fully oxidized form of the enzyme. The changes in the macrocycle vibrational modes are consistent with a Ca2+-dependent increase in the out-of-plane distortion of the low-potential heme, the proposed peroxidatic heme. Most of the increase in out-of-plane distortion occurs when the high-affinity site I is occupied, but a small further increase in distortion occurs when site II is also occupied by Ca2+ or Mg2+. This increase in the heme distortion explains the red shift in the Soret absorption band that occurs upon Ca2+ binding. Changes also occur in the low-frequency substituent modes of the heme, indicating that a structural change in the covalently attached fingerprint pentapeptide of the LP heme occurs upon Ca2+ binding to site I. These structural changes may lead to loss of the sixth ligand at the peroxidatic heme in the semireduced form of the enzyme and activation.
Original languageEnglish
Pages (from-to)6570-6579
Number of pages10
JournalBiochemistry
Volume40
Issue number22
DOIs
Publication statusPublished - 5 Jun 2001

Keywords

  • Fingerprint peptide
  • Heme

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